Sometimes you discover things by accident, even if they were probably there for years.I had the same case when I discovered that GNOME allowed the use of a compose key and it was available right from the keyboard settings. Eureka moment? Sort of.Allow me to share my 'discovery,' but before that, let me briefly tell you what a compose key is.What is a Compose Key?A compose key followed by two or more keystrokes lets you type special characters and symbols like ® (registered), © (copyright), and à. You do it directly with your keyboard without having to hunt them down online or dig through character maps. This is particularly helpful for people who type in European languages like French, Swedish, etc on a QWERTY keyboard.You'll have to enable the compose key first. I am using GNOME desktop environment in this article, but a similar feature should also be available in other desktop environments. Enable the Compose Key on GNOMESearch and open settings from the GNOME Activities overview.Open SettingsInside the settings, go to the Keyboard section. Here, you can see an option for Compose Key.It is set to Layout default in my Ubuntu 24.04 installation using GNOME 46 and was turned off by default in my Arch installation using GNOME 48.Select Compose KeyIn any case, go inside the compose key and either enable it (in case it is turned off) or disable the default layout.Set another Compose keyAs soon as you do this, you can see that you can now set another key as the compose key.I set the Right CTRL key as the compose key, as shown in the screenshot above.🚧If you are using VirtualBox, do not assign the Right-CTRL key. Because in VirtualBox, it is the host key with some special usage.That's it. Whenever you need to type some special symbol, first press the Compose key. This changes the cursor to a special look. Enter the code for the character you want to enter. 0:00 /0:17 1× A small clip showing the working of the compose key in GNOME. Essential compose key codesYes, you need to know the character code. This may seem like an additional burden, but for frequent users, it will soon become muscle memory.Press the compose key you had set earlier followed by the sequence of characters shown in the left column and it will output the characters in the second column in the table below:Compose Key PlusTypes Character' aá" aä` aàa eæo o° Degree symbolo c©o r®s o§t m™ (Trade Mark)> >»<