Season Four, also known as Day 4 of the television series 24 premiered on January 9, 2005 and aired its season finale on May 23, 2005.
Season Five, also known as Day 5 of the television series 24 premiered on January 15, 2006 and aired its season finale on May 22, 2006.
Season Six, also known as Day 6, of the television series 24 premiered on Sunday, January 14, 2007. It premiered on Sky One in the UK on January 21 2007, with two episodes, then there will be two episodes the following week, and another two the week after, before having only one episode per week. The Australian premiere was on Tuesday January 30, 2007.