Skills represent what your character has learned through training, background, or raw talent. They are tied to specific abilities (like Strength or Intelligence) and are used whenever a character attempts something challenging and non-combat-related.
When attempting a task that requires skill, you roll a d20 and add the appropriate bonuses:
The GM sets a Difficulty Class (DC), and if your result meets or exceeds it, you succeed. GMs may allow partial success or impose consequences on failure.
Your character gains skill proficiencies from their species and class. Each class also lets you upgrade a number of skills to Expertise.
Expertise means you double your Proficiency Bonus when making checks with that skill.
1d20 + 2 (INT) + 6 (Expertise) = 1d20 + 8
Some species may also grant Expertise in specific areas, allowing for more specialized builds.
Each skill is tied to an Ability Score. Your modifier for the skill is based on that ability, plus any bonuses from proficiency or expertise.