I recently swiftly mentioned DRM over at MangaWorthReading, and didn't feel it fitting getting deeper on that blog, so I decided to write my own blog post.
Short about DRM
DRM, short for Digital Rights Management, is a broad term for technical mechanisms to limit how customers can use media or devices they have paid for. This can be to prevent making illegal copies, but it's also used for artificial market segmentation or artificial product differentiation. There's a few ways DRM works, most common talked about in my circles, is where a piece of software authenticates the use of a product, like a game or movie. These systems can be everywhere from seamless and painless, like often is with iTunes, Google Play and Netflix, to slow, buggy and even hostile.
The Bad Stuff
An issue with DRM is, the purchaser is constrained to use the product as intended, be it with only the intended software, in intended region or otherwise. The purchaser does not have the freedom of choice to do as they wish with the product. Often, the DRM refers to encrypting the product and contacting a server before the product can be used by the purchaser.
These two factors attributes to people calling DRM a rental or leasing contract, rather than an outright purchase. I've also heard people saying that buying digital will always mean renting the product, though there's a lot of digital stores: HumbleBundle, GOG, HDTracks and more who pride themselves in selling DRM free. Well, in the case of HumbleBundle, it's a mixed bag of DRM-free and DRM'ed software.
The Good Stuff
It is not uncommon to see code signing being used for DRM; iOS has no Apple endorsed way to sideload apps, and while this is inconvinient for tinkeres, this is a means to protect the user from malicious software. The Apple provisioning tools are made in such a way that Apple can retroactively disable apps on all devices, made for malicious software that's slipped through App Review, but could be used if Apple no longer endorse a given app.
Android on the other hand, does allow for sideloading, but is not enabled by default for the same reason given for iOS. Google letting tinkeres install any app on their phones, enables for much greater flexibility, but I won't recommend sideloading to the average user, because of the higher risc of malicious software. There are ofcourse valid reasons to sideload, such as installing the Amazon AppStore.
Personally I try and shop DRM-Free whenever possible, I much prefer the freedom it gives and in cases where it's difficult to find a DRM-Free copy, it's fortunately legal in the Denmak to remove DRM, if it's to use on an otherwise unsupported personal device. It has to be said that copying of digitally purchased material is illegal regardless of DRM or not, meaning that even sending your mates your copy of games from GOG is piracy, so please don't abuse abuse this power!