They're currently in their 10th season. They joined the NFL as an expansion team in 2002.
23 years old ..As of June 10 ,2010
At http://www.houstontexans.com/team/texansteamhistory.asp the name history is explained. Look under '2000' ('Feb.', 'April', and 'Sept. 6').
The Houston Texans joined the NFL in 2002. They were an expansion team and were always based in Houston, TX.
Houston is 42 years old (birthdate: March 24, 1969).