Apps are the cornerstone of iOS. The ecosystem is what sets Apple's mobile platform apart from its rivals, and the highest-quality iPhone apps are typically best in class.
But, like any app store, it is sometimes difficult to find out what are truly the best apps, the ones that stand out from the rest - because they offer a tool or service that is far beyond anything else available.
Sometimes the best apps are free, other times you will have to pay a little bit for them. Here we showcase the best available and offer up everything you need to know about the app and how much it will cost.
This round-up compiles our favourites, from top-quality creative tools and video editors to the finest productivity kit and social networking clients.
As always, if your essential app isn't on the list - let us know in the comments...
1. Drafts ($9.99/£6.99)
It would be easy to dismiss Drafts as a mere note-taker, but it's far more than that. Although you can use it as such, the app's hugely powerful actions system provides the means to create complex workflows to boost your productivity. Markdown support, plentiful sharing options, and archive search ensure it's a must-have.
2. Hours Time Tracking ($7.99/£5.49)
Hours is a rarity - a time-tracker that you'll actually use. The interface is simple and smartly designed, all bold colours and big switches. Over the day, the app builds a visual timeline, so you can see where your hours went; and on iOS 8, a Today view widget enables you to get at your timers from anywhere.
3. PicFrame ($0.99/69p)
Sometimes, the simpler photo editing tools are the ones that really stand out. For a tiny amount of money, PicFrame gives you a large selection of frames, into which you load your pics. You then add some styles and captions before exporting the entire lot via email or social networking.
4. Air Video HD ($2.99/£1.99)
Even the most expensive iPhone has a fairly limited amount of on-board storage, and this is a problem if you have a large video collection you'd like to access. Air Video HD server streams (and if necessary, re-encodes) files from a PC or Mac that can then be played on your iPhone; there's AirPlay support, and also the means to access your Air Video server over the web.
5. Byword ($4.99/£2.99)
Byword is a text editor that hits the sweet spot of being both usable and simple. Its font is clear, and a toolbar adds live word count or Markdown buttons. Your documents can be saved locally, to iCloud, or to a linked Dropbox account. Output can also be exported to various formats (PDF; HTML; email) or to a blog if you buy the $4.99/£2.99 'Publishing' IAP.
6. ProTube ($1.99/£1.49)
You might baulk at the prospect of paying for a YouTube app, but with ProTube you're getting a better experience. For a start, it's ad-free, and the layout for video pages beats the official client. Additionally, you can choose a default video quality, create offline playlists, and leave audio playing in the background.
7. Scanbot Pro ($1.99/£1.49)
There are quite a few apps that turn your iPhone into a scanner, but we really like Scanbot. It's fast and makes it simple to enhance and crop your scans. Pay the one-off pro 'IAP' and you can add some surprisingly accurate OCR, passcode/Touch ID protection, and full text search.
8. Sky Guide ($1.99/£1.49)
Easily the most beautiful of the iOS stargazing apps, Sky Guide also happens to be the most usable. You can quickly and easily scan the heavens by dragging your finger around, optionally orienting the screen to wherever you happen to be looking. A Today view widget adds information about rise and set times for nearby planets, the sun and the moon.
9. Day One ($4.99/£2.99)
Traditional journals are all very well, but there's something wonderful about an app that you always have with you, into which you can save messages, images, locations and more, and then later retrieve everything via a search. Day One is beautifully designed and easy to use - best-in-class on the iPhone.
10. Fantastical 2 ($3.99/£2.49)
Fantastical 2 betters iOS 7's iffy Calendar app by way of a superior interface, a non-hateful method of dealing with reminders, and truly exceptional event input. The app has a powerful parser, and so while adding an event, you can enter the likes of "TechRadar lunch at 3pm on Friday", watching a live preview build as you type.
11. Figure ($0.99/69p)
Figure crams Reason's rich history of classic-era electronic music apps into a shoebox. Via a mixture of dials and pads, you can create all manner of banging choons, and then export them and assault your friends' eardrums. It's a fun toy for anyone, but also has the chops to be part of a pro-musician's mobile set-up.
12. iMovie (free with new devices or $4.99/£2.99)
Camera enables you to do the odd bit of cropping with video files, but iMovie is an audacious attempt to bring a full video editor to your iPhone, infused with the ease-of-use its desktop counterpart is renowned for. Amazingly, it succeeds. Effects, themes, credits and soundtrack creation then provide extra polish for your mobile filmmaking.
13. Launch Center Pro ($4.99/£2.99)
More or less a speed-dial for regularly performed tasks, Launch Center Pro can be a huge time-saver. You can create shortcuts for things like adding a new Tumblr post or sending your last photo to Twitter, and these shortcuts can be arranged in groups. An essential purchase if you heavily use even a handful of the [supported apps](http://actions.contrast.co).
14. Transmit for iOS ($9.99/£6.99)
The app that defines iOS 8, Transmit for iOS is also a missing link for anyone who wanted a file manager for their iPhone. It might have roots in an OS X FTP client, but Transmit for iOS also integrates with cloud storage and local networked Macs. It's perfect for moving documents, renaming files, and creating archives to email or upload.
15. Unread ($4.99/£2.99)
There are RSS readers that are more efficient, but Unread is the most pleasant to use. The interface begs you to sit back and take in articles from feeds you're subscribed to, and plentiful share options enable you to send content onwards. Note that although this is a free download, it's essentially for a demo; the full-price unlock gets you the regular app.
16. Weather Pro ($2.99/£1.99)
There are prettier and more stylish weather apps, such as Dark Sky (which we're also rather fond of), but it's WeatherPro that gets our vote, largely because of its accuracy. But it's also information-rich, with radars and detailed forecasts for your favourite locations.
17. Numbers (free with new devices or $9.99/£6.99)
When Apple first brought its office-style apps to iPad, that was impressive, but squeezing them down to iPhone size seemed impossible. Yet Numbers in particular remains surprisingly usable, not least when you create forms to rapidly enter data while on the go. iCloud sync provides access from Macs and also PCs via Numbers for iCloud.
18. Pocket Casts ($3.99/£2.49)
Apple's Podcasts app has improved since its initial launch, but still falls short of Pocket Casts. The third-party app cleverly mixes elegance and character, with a friendly, easily browsable interface. Subscriptions can be filtered, and you can stream episodes of shows you've not yet downloaded.
19. ProCamera 7 ($4.99/£2.99)
This app takes your iPhone's camera to the next level. ProCamera moves beyond Camera in offering more modes, including rapid-fire, anti-shake and night shooting; there's a dedicated lightbox for managing images; and dozens of filters are built-in, along with an impressive selection of editing tools.
20. Soulver ($1.99/£1.49)
Soulver eschews trying to recreate a traditional calculator on your iPhone. Instead, it's akin to jotting down calculations on the back of an envelope, but a magic envelope that pulls the numbers from your in-context sentences and gives you a total. Live currency conversion is built in, and you can save calculations and sync them via Dropbox or iCloud.
21. The Elements ($13.99/£9.99)
Originally the darling of the iPad, The Elements in late 2013 became a universal app, so it could be enjoyed on iPhones too. A rich, engaging digital book, it tells the story of the periodic table. Each of life's building blocks can be manipulated on the screen, before you delve into related facts and figures.
22. Traktor DJ for iPhone ($0.99/69p)
Traktor DJ on iPad is a fantastic DJ app, enabling you to work with waveforms rather than just bunging two virtual spinning records on-screen. Cramming that into an iPhone seems like madness, but somehow it works. There's more zooming and swiping, but otherwise everything's here, from EQ to tempo controls.
23. Tweetbot ($4.99/£2.99)
The king of iOS Twitter clients remade for iOS 7 is a wonderful thing. Managing to combine Apple-style sleekness with developer Tapbot's playful nature, Tweetbot is a fun, feature-packed app. As a basic client, it works, but as an app for heavy Twitter users, it excels through its flexibility and wealth of settings.
24. Vert 2 ($1.99/£1.49)
There are a lot of conversion apps about, but Vert 2 caught our eye through an interface that prizes clarity above all else. Beyond that, a combination of smart filtering and customisation cements the app's place on your home screen. And if you don't like the theme, you can easily make your own.
25. vividHDR ($1.99/£1.49)
We've never been overly impressed with Apple's HDR, and it pales in comparison to vividHDR. The basic concept is the same: stunning, vibrant photos, capturing amazing details in both highlight and shadow. But vividHDR's combination of speed, presets and 'before and after' comparisons results in better photos - and that's what really matters.
Best iPhone apps: 26-50
If you live in one of the supported cities, fire up Citymapper and you'll instantly forget any other travel assistant exists. The app is astonishingly good at getting you from place to place, whether you want to go by public transport or on foot. You get cost estimates for the former and a calorie count for the latter, and you just have to love an app that also estimates your journey time should you be wearing a jetpack.
Storehouse is all about telling stories with the help of gorgeous photos and videos. Although you can submit your own tales, you can also just take in other people's submissions, on anything from amazing journeys in the jungle through to meticulously prepared meals.
Most third-party keyboards for iOS are a waste of time, but SwiftKey's definitely worth a look. Rather than you laboriously tapping individual keys, you instead swipe your finger around, whereupon the keyboard figures out what you were trying to say. It's pretty accurate, and it only gets better the more you use it.
Plenty of apps exist for transferring content between your computer and your device, but Dropbox is free and easier to use than most of its contemporaries. Dump files you want to sync in a folder on your computer and Dropbox for your device will enable you to access them, download them for offline viewing, and, in many cases, view them.
On using the eBay app, there's a good chance you won't go near the eBay website again. The app is fast, has great saved searches (which flag new finds), and enables you to create listings. The last of those things is also improved by the built-in bar-code scanning.
Clients to access the popular Evernote service for storing notes and ideas online are available for so many platforms that we half expect a ZX Spectrum app to be announced tomorrow. On the iPhone, Evernote is efficient and usable, enabling you to rapidly scan your notes and also create new ones.
The world's biggest social network brings a tightly honed experience to the iPhone and iPod touch, but nonetheless still enables you to access your contacts, feeds and other important information. This sense of focus makes it in many ways superior to using Facebook in a desktop browser.
33. Find My iPhone
For the paranoid souls out there (or the unlucky ones who've had their devices pilfered), Find My iPhone is a must-have download. Assuming you've a 2010 or later iOS device, you can set up a free account and locate your devices within seconds. (Note that older devices can also be added to Find My iPhone - you just need a recent one to get things going.)
Apple's GarageBand turns your iPhone into a recording studio. Previously a paid app, GarageBand now has a freemium model. For no charge, you get full access to its features, including a range of smart instruments, MIDI editing and song arrangement. The only limitation is that relatively few instruments are included, but more are available via IAP.
35. Google Maps
When Apple removed Google's data from its Maps app, seemingly half the internet went nuts. In hindsight, the decision has been beneficial, because it resulted in Google creating its own mapping app, Google Maps. Bar some mildly irritating signing-in nonsense, this is a first-rate application - the interface is straightforward, the mapping is accurate, and it's also a means of getting Street View back on to your iPhone.
If you've a large music collection, it can sometimes be difficult to decide what to listen to next. Groove tries to figure out your listening habits and cross-references your collection with Last.fm data. The result is constantly evolving automatic personalised playlists that might just change your iPhone music-listening habits for good.
Take a photo, smash a filter into it, and upload it. Instagram's service is now used by millions of people to share nuggets of visual loveliness, and the app itself is a pleasure to use, and also to browse during moments when you're not feeling quite so inspired.
Watch live TV and browse featured and recent BBC shows in the BBC iPlayer app. There's a favourites section to get easier access to your top shows, and AirPlay support for firing footage at your Apple TV. (This uses the system AirPlay functionality - start playing a show, double-click the Home button, swipe right twice, then choose 'Apple TV' from the AirPlay button.)
39. Movies by Flixter
Although some aspects of cinema listings app Movies by Flixter are disappointingly US-centric (notably regarding details on upcoming movies and DVDs), it succeeds where it matters. Select a film and the app figures out where you're located, lists nearby cinemas, and displays times your chosen film is showing. Efficiency can be further increased by pinning favourite cinemas to the top of the list.
Brits might rightly grumble that the Netflix selection leaves a little to be desired, but it's still a very affordable way to get a ton of TV in front of your eyes. The app works much like you'd expect: browse, watch, realise it's three in the morning - again.
Although iOS includes iCloud Keychain, 1Password is a better system. It's fully cross-platform and enables you to store multiple identities (such as a full one for payments and a simplified one for forums), secure notes and software licence details. As of iOS 8, 1Password integrates with Touch ID, meaning you can use it with Safari, although the app also retains its own built-in browser.
Instapaper was the app that kicked off the whole 'read later' thing, giving you a way to save web pages for later. It's still the best, boasting a fantastic and readable default theme — and now it's free. Perhaps more importantly, it also fully integrates with iOS 8, meaning you can now directly save to Instapaper from any browser that supports Share sheets.
43. TodoMovies 3
TodoMovies is a to-do list for movies. You use it to browse what's on (and, if you like, what's been on — including years ago) and build a list of what you want to see. Cleverly the app also enables you to rate each movie, thereby building up a list of your favourites that you can refer to at any time.
The remote for Apple TV is a bit of a joke when you need to do anything more than play or pause. Remote is a free app which provides much better control and the ability to stop yourself going mad when typing things into search fields. It'll also happily use Home Sharing to pull content from computers on your network to your device, or fire said content at your Apple TV using AirPlay.
The prospect of Nike+ but better and for free might sound unlikely, but that's what RunKeeper provides. Previously split into 'pro' and 'free' versions, the developer now generously includes all the features in one free app.
That means you can spend no money, yet use your iPhone's GPS capabilities to track your jogging and cycling routes, and examine mapping and details of your pace and calories burned. Activities can be shared online, and treadmill runs and other exercise details can be entered manually.
FaceTime is a great alternative to standard voice calls, but it's no good if you're trying to contact someone without a Mac or compatible iOS device. Therefore, Skype remains an essential download. The interface is simple and usable, enabling anyone with a Skype account to make free calls to other Skype users and cheap calls to anywhere in the world. If you're on Pay and Go, this is particularly handy, but the app also enables iPod touch users to utilise their devices for calls.
TED is brain food. The app provides access to talks by insanely clever people, opening your mind to new and radical ideas. You can also save your favourite talks locally, for even easier access, or ask the app to inspire you, based on your mood and available time.
The official Twitter app might lack some of the features found in the likes of Tweetbot, but it does provide a sleek and simple means of using the service. It also rapidly rolls in new features from the website, such as the Connect and Discover views, along with expandable tweets that contain photos and videos.
49. TuneIn Radio
Don't bother buying a DAB radio - just install TuneIn Radio instead and plug your device into a set of speakers. TuneIn Radio has a great interface for accessing over 50,000 digital stations; it also has AirPlay support, and you can use it as an alarm clock.
The Wikipedia website works fine on iPhones, but a dedicated app is a better bet. Wikipanion is a freebie which gives you quick access to article sections, in-article search, viewing options, bookmarking, and the ability to tweet about whatever odd fact you've just unearthed. Also, wonderfully, there are no ads.