How to ban or unban from iptables

How to ban or unban an IP address with iptables

Simple (where 25.55.55.55 is the IP address we want to ban/unban)

Ban:

iptables -I INPUT -s 25.55.55.55 -j DROP

Unban:

iptables -D INPUT -s 25.55.55.55 -j DROP

See How to unban from fail2ban