There are many levels in Dead Frontier. The lowerest is Lv 1 and the highest is Lv 220. The higher the level the further you go into the city. Every level you level up you get 5 free points to ugrade your character. Until Lv 50+ you only get 1 or 2 points to upgrade your character.
TIP: always level up melee skills every few levels you level up, because it's going to be useful as you level up higher. Another tip is that if you upgrade endurance skills very high your you can run more longer due to higher endurance. You can also get more health points.