Total XP is a ranking system. The score from all games played on official servers will be added to a database and a rank will be shown the main menu of the game.
Earning Total XP
You earn Total XP on public servers. Once a game ends, all players that are in either NF or BE add their score to their Total XP. Only up to 100 points can be earned per game.
Total XP can only go up. If your score is negative at the end of a game you will earn 0 Total XP.
Team Change Penalty
Players that switched team during a match (including spec) will get a score penalty at the end of the game. Joining from spec results in a 50% reduction in XP gained. If you're on BE or on NF and you leave your team you get a 90% reduction in future XP points gained.
If you choose a specific team instead of autojoining you get a 25% XP reduction.
Choosing "Auto-assign" on the team selection menu will give you a small bonus to your Total XP.
Your rank is shown in the lower left corner of the game's main menu. It is calculated by counting the number of players with lower Total XP than you. This means that the player ranked highest will have a rank equal to the number of players in the database.