A "mission" is a generic term for work offered by a station, as well as a few other interactive tasks. Trade missions can be found at nearly every station - one of the trading guilds with offices at the local station may have cargo that needs to be delivered or retrieved. Your nation may offer you combat practice missions, where you'll be asked to kill rogue AI bots in the station's vicinity. Border patrol missions, spy missions, prospecting missions, and a number of other mission types are available depending on the station, your license levels, and your faction standing. Also, some missions will be available to groups of players that single players don't have access to.

In addition to these job postings, you'll also find tutorials and license tests listed with the missions.

Most missions will give you some sort of reward. Often this will be monetary, but you will also earn more skill points when participating in missions than you would otherwise, and sometimes you can earn special rewards or medals.

More information on interacting with missions is available at the Mission Interface page.