You never watched one episode? Then why ask the question?

Here's what Wiki says:

"Lost is an American television series that originally aired on ABC from September 22, 2004 to May 23, 2010, consisting of six seasons. Lost is a drama series that follows the survivors of the crash of a commercial passenger jet flying between Sydney and Los Angeles, on a mysterious tropical island somewhere in the South Pacific Ocean. The story is told in a heavily serialized manner. Episodes typically feature a primary storyline on the island, as well as a secondary storyline from another point in a character's life."