Player progression system Overwatch Guide
The game features a player progression system. When gaining a level, the player's account receives a loot box, allowing him or her to unlock additional bonuses. It doesn't matter which character you choose for the duration of a match, as the experience you have gained is accumulated on your player account. After pocketing a level, you get a loot box to boot, simple as that.
Inside every box you will find four random items. Those can be character skins, emotes, victory poses, player portraits, additional sounds (lines spoken by the characters), or tags. The items are divided into following classes: common, rare, epic and legendary. In each box you will find one item that is guaranteed rare or better. No additional items, such as a key, are required to open a box.