League settings are the rulebook for your fantasy football league. They decide how many teams are in the league, how many players start at each position, how many bench spots you get, and how points are scored. Before your draft even begins, these settings shape which players are valuable and which ones are not. A running back who catches passes is worth much more in a point-per-reception (PPR) league than in a standard scoring league.
Common settings include scoring format (standard, half-PPR, or full PPR), roster size, starting lineup slots, and rules for quarterbacks such as superflex or two-QB formats. Settings also cover how waivers work, how trades are reviewed, whether there is a trade deadline, and how playoff seeding is decided. Two leagues can play with the exact same players but feel completely different because of these rules.
Always read your league settings before drafting and before making any roster move. Managers who know their settings gain an edge, because player value changes based on the rules. For example, a tight end premium league awards extra points for catches by tight ends, which pushes that position up the draft board.