Why would you need to clean your device?
It is not uncommon for people to believe that their iPhone, iPad or iPod Touch are completely fool-proof and they never get viruses or junk to clog them. This actually not true. iOS can indeed get clogged by junk due to applications leaving residual "caches" or "cookies" and other sorts of data even after being uninstalled. This data gets stored in the containers of the applications (iOS uses a concept called App Sandboxing) and it starts occupying a significant chunk of space after some months of usage.
Is this normal?
Yes. Most operating systems use caching and data for the applications to be able to store their temporary stuff, images, audios, clips, user data, scores and tops for games and so on. Some of these things are stored in the Keychain (if they're sensitive), but most of it resides on the user partition. iOS is no exception. In many cases we clog our devices with useless photos we don't need anymore, temporary files from apps we don't even use that often or even apps we haven't touched in several weeks. All these things will eventually make your device to act slow, backup things painfully slow due to the big amount of data, maybe most of it not needed, and it can even create storage issues – you won't have enough space for your precious moments if the storage is filled with junk, would you?
So what can you do?
Since iOS itself does not provide a method to clean up the device, we will resort to software like iMyFone Umate iPhone 
Cleaner. Best thing? iMyFone currently runs a campaign where you can get the software FOR FREE! It is their 3rd-year anniversary and they've decided to give this gift to the community. Their software cleans out your device's junk, compresses photos in a lossless format to squeeze more space out of the file system and backs up the large files to release the used space.
You can obtain iMyFone's Umate iPhone Cleaner for FREE just by sharing their 3rd-year-anniversary promotion on Twitter, Facebook or other social media. You can get Umate iPhone Cleaner for free here.
The lucky wheel
Since iMyFone's catalog of software is not limited to iPhone Cleaner, they also have a promotion where you can spin the lucky wheel and earn big coupons for their software. Every user has 2 spins so technically, you are able to get 2 coupons if you're lucky. You can save from $5 up to $10 on any product. You can spin the lucky wheel here
What's next?
Celebrating their 3rd-year-anniversary in mobile devices software production, iMyFone will release in April a new product called TunesUp. If you remember Umate iPhone Cleaner, TunesUp will be somehow like a continuation, but on your computer. We often backup our devices. A backup typically contains, amongst other system-related files, your photos, videos, applications data, voice records, notes, phonebook, messages, etc. The backups can also contain junk pulled over from the device, therefore, when you restore a backup, you would inevitably restore the junk as well. This is where TunesUp comes to help.
The program cleans iTunes media backups, software update errors and attempts to fix some of the common iTunes errors that may occur during backup or software update. It makes a great pair with iPhone Cleaner. For the moment, the program isn't released. The release is scheduled for April. the price is also unknown for the moment, but you can apply for a pre-sale 50% off coupon just by using your e-mail address which is nice. You can get your 50% off coupon here.
Full disclosure: This article has been sponsored by iMyFone.
