Five named variants, correctly explained — including the one most sites get wrong. Not beginner rules content; this assumes you already play.
The Idaho Straddle
Also known as “Ultimate Last Action”
Some poker rooms allow a straddle from UTG or the button, and then a restraddle from anywhere else at the table — small blind, MP1, wherever. Whichever straddle is posted last gets ultimate last action preflop only. Normal position and action order resumes for the flop, turn, and river. This is distinct from a standard Mississippi straddle, which allows a straddle from any position but has no restraddle-chaining or last-action mechanic.
Restraddle
From any position
The classic. A straight straddle posted by the player directly left of the big blind, live to raise when action returns.
Posted from anywhere, with priority typically going to the button first. From the button specifically, it gives last action both preflop and postflop.
The escalating version — UTG straddles to 2x, the next seat restraddles to 4x, the next to 8x. The "standard" definition most glossaries use.
Posted from any position, but only becomes live if nobody raises before the action reaches it. The trap variant.