Free multimedia APIs from Microsoft
DirectX is a free collection of APIs (application programming interfaces) for programming graphics and sound. This allows developers, primarily game developers, to easily create fully-featured games that run on Windows. Most users aren't even going to notice DirectX working - it just runs when it needs to, without telling you. Interacting with it otherwise is a little more complex and will need programming know-how.
Free tool to control sound and graphics cards
DirectX is a technical tool that helps game developers interact with sound and graphics cards. Although it can be installed on any computer, most users won’t ever need it. It runs when you play a game made with DirectX and that’s it. You’re only going to need to get to know it better if you want to program with it yourself. It has one of the most agile runtime processes amongst this category.
What is DirectX used for?
DirectX is a set of Windows interfaces. Developers program to the DirectX API, which lets their programs - often games - interact correctly with sound and graphics cards. In turn, makers of sound and graphics cards recognize DirectX, so they know what to do when a program made with DirectX accesses their functions.
Do you already have DirectX?
Since DirectX doesn’t have an interface like other apps (it won’t appear in your apps list, for example), you’ll have to get a little more technical to check if it is already installed on your computer. To check, follow these steps:
The DirectX installation
If you find that DirectX is not installed on your computer (or the version is very old), you’ll have to download DirectX again to use it. The download is simple and how you might expect - you download and run the .exe as normal. The installation is slow, which might prove a little frustrating and - watch out - the app tries to install Bing during installation.
How do you open the DirectX control panel?
Since DirectX isn’t a normal app, you can’t open it in the usual way. Instead, press the Start button and type “dxdiag” into the box. Your computer will ask you if you want to run DirectX.
The window that opens is a very traditional-looking Windows interface. All the data it provides is just informational - lots of details about your system, the display settings, rendering features and drivers, sound information, and current input devices. You don’t interact with this information - there’s an error window and, if you’re programming and make a mistake, the error will show up here. You go back and fix it, and the error will disappear.
Who needs DirectX?
There are two situations in which you might need DirectX.
It's worth bearing in mind that DirectX isn't the only tool of its type. There are other APIs that interact with graphic cards, and many of them are more modern. You can compare this with a valid app like Runtime, That said, if you're playing or developing certain games or on certain (probably older) machines, you might well need it.
A tech tool most won’t need
DirectX is a solid piece of technology that's been around for years and still going strong. The graphics and sound technology work very well (which is why it's still relevant even though it's very old), and the interface is very usable, even though it's very old-fashioned.
Most of us, however, will never see it - unless you're programming, you'll never even have to open it, as it will just run in the background without you noticing. DirectX isn't really the kind of software that you want or don't want. If you need it, you'll have to install it and it's a pretty painless experience.
The most recent version of DirectX improves Windows 10 compatibility and adds Variable Rate Shading (VRS) support. Other recent versions added DirectX Raytracing support, Depth Bounds Testing, and Programmable MSAA.