Apt

1 Repository

A repository is a collection of files that contains information of softwares like the version and other details. The repository is basically a web URL and official repositories are stored in /etc/apt/sources.list. When you use sudo apt update, the system will download the information from the repositories. And when you use sudo apt install <application>, the system will know where the application locates via the information.

2 PPA

PPA stands for Personal Package Archive. The PPA allows application developers and Linux users to create their own repositories and distribute software other than Ubuntu default repository. With PPA, you can easily get the newer software version that is not available on the Ubuntu official repositories.

2.1 Add PPA

# Add a PPA.
# This will add the repository to the directory `/ect/apt/sources.list.d`.
# This usually will create two files. One is the list file, the other is the backup file with suffix 'save'.
sudo add-apt-repository <PPA>
# Download the information of the software.
sudo apt update
# Install the software.
sudo apt install <software>

2.2 Delete PPA

sudo add-apt-repository --remove <PPA>