The user file in Plants vs. Zombies contains data about your progress in the game, money, unlocked modes, trophies, achievements, purchased items, plants in your Zen Garden, and your Zombatars. By directly modifying the user file you can change any of these things, and do certain things that are either very difficult (like earning $999,990) or not possible in the game (like having a Cob Cannon in your Zen Garden). You can also do things that are very easy if you want.