Table schema:
CREATE TABLE Skills (skill_id VARCHAR, skill_description VARCHAR); CREATE TABLE Skills_Required_To_Fix (skill_id VARCHAR)

Question: Which skill is used in fixing the most number of faults? List the skill id and description.
SQL: SELECT T1.skill_id, T1.skill_description FROM Skills AS T1 JOIN Skills_Required_To_Fix AS T2 ON T1.skill_id = T2.skill_id GROUP BY T1.skill_id ORDER BY COUNT(*) DESC LIMIT 1