# To search a package:
apt search package

# To show package informations:
apt show package

# To fetch package list:
apt update

# To download and install updates without installing new package:
apt upgrade

# To download and install the updates AND install new necessary packages:
apt dist-upgrade

# Full command:
apt update && apt dist-upgrade

# To install a new package(s):
apt install package(s)

# To uninstall package(s)
apt remove package(s)