List all upgradable packages:

sudo apt list --upgradable

Updating a single package:

sudo apt install --only-upgrade <package>

Searching for a package:

apt search php
apt search mysql-8.?
apt search mysql-server-8.?
apt search httpd*
apt search ^apache
apt search ^nginx
apt search ^nginx$

List installed packages:

apt list --installed

List package dependencies:

apt depends <package>

List package dependencies recursively:

apt rdepends <package>

Hold / unhold a package (prevents it from being upgraded):

sudo apt-mark hold <package>
sudo apt-mark unhold <package>

Reinstalling a package:

sudo apt reinstall <package>

Editing the apt sources:

sudo apt edit-sources