A straddle in poker is an optional blind bet made by a player before the cards are dealt. It is usually twice the size of the big blind and allows the straddling player to act last preflop. It increases the stakes and creates more aggressive play in the following betting rounds.
Straddling can only take place in poker cash games and is not something you can do in poker tournaments. If you didn't know, you can also straddle when playing online poker cash games on sites like TigerGaming.
There are plenty of reasons to play real money online poker at TigerGaming.