Most modern distributions have a way to access keyboard accessibility options in the desktop environment.

Different desktop environments have a different way of controlling keyboard accessibility settings. Also, different versions of a desktop environment can change how you control keyboard accessibility settings. Following are some examples.

KDE

1. Select the distribution icon at the bottom left-hand corner of the desktop and select Applications > Settings > System Settings.
2. In the System Settings dialog box, select Accessibility.

GNOME

1. Select Activities > Show Applications.
2. Select Settings.
3. Select Universal Access.
4. In the Univeral Access pop-up box, scroll down to the Keyboard section.

XFCE

1. Select Applications > Settings > Accessibility.
2. In the Accessibility dialog box, select the Keyboard tab.

Keyboard

Sticky Keys makes it so that the Shift, Ctl and Alt keys on the keyboard "stick." For example, let's say you have a user who struggles to hold down the shift key and press a letter on the keyboard to capitalize a letter. By enabling sticky keys, the user would be able to press and release the Shift key, and then type a capital letter. For example, pressing and releasing Shift and then typing "hello" would print Hello.

Slow Keys makes it so that the key on the keyboard must be depressed for a certain amount of time before the keyboard starts to accept input. By default, keyboard strokes respond instantly. By enabling slow keys, you can configure the system to wait anywhere from 50 to 20,000 milliseconds before responding. It is noteworthy to recongzine that slow keys does not slow every single keystroke if bounce keys is not enabled. Once the first key has been depressed long enough to start accepting input, all of the following keystrokes are instant. When the keyboard is not used for a short while, slow keys is reset to require the first keystroke to be depressed for some time to start accepting input.

Bounce Keys makes it so that every key stroke is delayed. By enabling bounce keys, every key must be depressed for 50 to 20,000 milliseconds before responding. This is useful for people that have a tendancy to mistakenly press a key numerous times. 

Toggle Keys makes a high pitched sound when a locking key is activated, and a lower pitched sound when a locking key is deactivated. Locking keys are Caps, Num lock, and Scroll lock.

Repeat Rate is the amount of time that elapses between each repeat of a key. For example, if the repeat rate is 1.1 seconds, when you hold down the A key, the letter A will appears once every 1.1 seconds.

Mouse

Mouse keys allows you to use your keyboard to move the mouse. The keypad is the numeric keys on the right side of the keyboard. The 8, 4, 6, and 2 keys can be used to move the mouse.

On screen keyboard lets you use your mouse to interact with an keyboard in the GUI instead of a physical keyboard. Each distribution has a different way of accessing the on screen keyboard. GOK is the abbreviation for the Gnome On Screen
Keyboard.

GNOME

1. Select Activities > Show Applications.
2. Select Settings.
3. Select Universal Access.
4. Toggle the Screen Keyboard selector to On.

When you interact with an application and accepts keyboard input, the on screen keyboard appears.

Gestures include both keyboard keystroke combinations that perform a certain function as well as mouse and trackpad combinations. As an example, in Linux Mint, Menu > Preferences > Keyboard will launch the keyboard dialog box. Selecting the keyboard shortcuts tab will allow you to view and modify or add keyboard combinations. Probably the most popular keyboard combination is Ctrl + Alt + L to lock the PC.