Experience

Experience (abbreviated as XP) is earned at the end of each match in Tribes: Ascend. XP can be used to unlock new classes or equipment, or to upgrade equipment already owned. The amount of XP gained depends on the outcome of the game, the length of the match, player performance, and if any Boosters are active. Players do not need to stay until the end of a match to earn XP; it will be awarded to the player the next time they log on after the match ends (NOTE: this is currently bugged. If you leave a match before the end you will NOT get XP). XP is earned on a global basis as of the 9th feb. 2012 patch. Prior to this it was split between the classes you used in the match. Experience may also refer to the XP gained toward a player's rank progression.

First Win of the Day
Players gain a flat 1200 XP bonus from their first win of the day. This bonus becomes available every day at 5 AM EST.

100 Tokens were also awarded before the 0.1.742.0 patch, but have now been made redundant.

VIP
Players can gain VIP status which allows them to earn XP 50% faster. VIP is gained by purchasing a Gold pack in the Tribes: Ascend store. Originally this was going to be a bonus for those who participated in the beta, however it seems that it will now be available to anyone who purchases gold.

Boosters
Boosters double the base XP a player receives in Tribes: Ascend, allowing classes, equipment, and perks to be unlocked at a faster rate. Boosters have a limited duration when activated, available in 1-day, 10-day and 30-day packages.

Boosters stack with the XP bonus obtained from VIP status. If a player received 1000 XP at the end of a match, the bonus from VIP status would increase it to a total of 1500 XP. With a booster active, the total would increase to 3000 XP, triple the base values.

Gold vs XP
Reddit has a detailed breakdown of Gold vs XP.