Escape from Tarkov features five skill categories that are trained through active use. In short, the more you use a skill, the better you get at it. Every skill can be leveled up to level 51 (elite level), this level provides an extra ability linked to the skill.
Since the 0.12.1.5413 update (24 Dec 2019), while leveling skills, the character will now have "exhaustion” of skill per raid, this means that skill will be leveled more slowly during the raid after every repeat. If you do not level a certain skill for a while (a few minutes), the character will recover and will be able to level this skill with normal speed again. This change is directed against skills abuse (targeted and consecutive leveling of the same skill).
Almost all actions in Escape from Tarkov grant the player experience. For example killing, looting or quest completions.
The table below shows the EXP required to level up and a cumulative total.