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. 1Password ($17.99/£12.99)
With iOS 7, Apple introduced iCloud Keychain, for entering and securely storing passwords and payment data. But 1Password is still worth investing in, for its wider support (platforms; browsers; websites) and the means to store multiple identities and secure notes. On iOS, it has its own built-in browser; alternatively, you can copy passwords to then paste into Safari.
2. Adobe Photoshop Touch ($4.99/£2.99)
This ambitious app aims to bring some of the power of Photoshop to your iPhone. Naturally, Adobe Photoshop Touch can't match the hugely expensive desktop app, but it nonetheless has a very good go for its tiny price tag, enabling you to work with layers, blend modes and a range of versatile tools.
3. 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.
4. Blur ($0.99/69p)
Sometimes the best apps are the ones that offer a seemingly effortless level of elegance. Blur merely takes one of your photos and enables you to blur and save it. The result: some of the most beautiful background wallpapers you're ever likely to see, made from your own images.
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. Capture ($1.99/£1.49)
It's frustrating to miss a moment you'd like to savour forever, despite being armed with an iPhone that boasts perfectly good video recording capabilities. But getting to the relevant settings in Camera can be fiddly. Capture does away with such messing around — launch the app and it immediately starts recording; quit and the app saves the video it's shot to your Camera Roll. It might not seem much but those seconds saved can make a big difference.
7. Clear ($4.99/£2.99)
While Apple's own Reminders app is mired in interface hell, Clear shows how it should be done. Lists are managed through gestural input, and urgent items at the top use a deeper red hue. iCloud sync enables your list to be up to date across all devices.
8. 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.
9. DM1 ($1.99/£1.49)
There are plenty of drum machines for iOS, but DM1 is easily our favourite. For beginners, there are pads you can tap and 86(!) kits to mess about with. Beyond that, there's a step sequencer and song composer, WIST, MIDI and Audiobus support, and export to iTunes, email and Dropbox.
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. GoodReader ($4.99/£2.99)
With iOS lacking a file system, surrogates are needed. Dropbox is great for general use, but GoodReader is an excellent solution for storing, viewing and searching all manner of documents, including PDFs, text files and images. It's packed with features and can connect to a huge range of online services.
13. 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.
14. 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).
15. Moves ($2.99/£1.99)
There are plenty of trackers available for iPhone, but Moves rises above its rivals through automatically recognising exercise types and providing you with a daily 'storyline' of your activity. And while the app itself isn't big on data sharing, it's easy enough to get your data out via Moves Export.
16. 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.
17. 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.
18. 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.
19. 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.
20. Star Walk ($2.99/£1.99)
Augmented reality isn't terribly exciting when it's a game showing a tiny alien doddering about on your desk, but when it involves the stars, it's a totally different and utterly mesmerising story. Star Walk is a guide to the heavens, but it comes to life when you overlay your screen on the night sky, enabling you to pick out constellations, planets and satellites with ease.
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.