Updated - January 25, 2020

1. The quick way

Before adding this PPA, please read the PPA's Description on their page which mentions important information about using it, which version is right for your Nvidia card and more. This is for desktop users who want the latest version of the driver or the last supported one for their card.

Using 18.04+ To install run the following command:

sudo add-apt-repository ppa:graphics-drivers/ppa

This will automatically update the repositories and then you can run the following line:

sudo apt install nvidia-driver-440

If your desktop does not load after installing the corresponding driver, then do the following:

sudo nano /etc/gdm3/custom.conf

then remove the comment (# symbol) from the line that says

# WaylandEnable=false

and save. Then reboot. If this still does not work, then please disable Secure Boot since you might actually be using UEFI.

2. Common questions regarding Nvidia

For Troubleshooting Nvidia Problems or Overclocking Settings please see this answer which covers:

1. What common bugs are solved by using the latest drivers?
2. My video card is not installing (Installation problems)
3. Tuning and Tweaking by Video card
4. Quick way of setting default screen resolution

Top questions asked about video cards discussed below:

1. Can I use the latest driver on an older version of Ubuntu?
2. Difference between video cards & drivers: Official Nvidia site, Ubuntu's Default, PPA & Nouveau?
3. What PPAs are recommended when using any video card?
4. How to know which driver or package to install?
5. How to install a driver?
6. Difference between Proprietary Drivers?
7. How to know if my video card is supported in Ubuntu?

2.1 Can I use the latest driver on an older version of Ubuntu?

Since 12.04+, video drivers are maintained and updated more often. It is easier to handle and solve the problems that showed with older ones. You most likely won't need additional PPAs unless you have the latest Nvidia card.