Pro Football Focus (PFF) is a website that provides in-depth analysis and advanced statistics for American football. Founded in 2006, PFF is known for its comprehensive grading system that evaluates the performance of individual players and units on every play of every game.

One of the primary features of PFF is its player grades, which are based on a proprietary formula that takes into account a wide range of factors, including a player's impact on the game, their consistency, and the difficulty of the plays they made. These grades can be used to compare players within a team or across the league, and are widely respected within the football community.

In addition to player grades, PFF also provides detailed analysis of teams and players, including scouting reports, position rankings, and projections for the upcoming season. The site also has a number of tools and resources for fantasy football players, including customized rankings, projections, and draft guides.

Overall, PFF is an excellent resource for anyone looking to get a deeper understanding of American football. Whether you're a casual fan or a serious analyst, there's something on the site for you.