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.