Certification is official confirmation that someone has met specific standards or requirements in a particular skill or area of knowledge. When a lifeguard receives certification, it means they've passed tests proving they can perform water rescues and CPR. When a teacher earns certification, they've demonstrated they know how to teach and understand their subject well enough to lead a classroom.

Think of certification as an official stamp of approval from an organization that has the authority to judge whether someone is qualified. A doctor must receive medical certification before treating patients. A pilot needs certification to fly an airplane. Even scuba divers, electricians, and computer programmers often pursue certifications to prove their expertise.

Certifications usually require passing tests, completing training, or demonstrating specific abilities. They're different from ordinary diplomas because they focus on particular skills rather than general education. Many certifications must be renewed periodically, requiring people to take refresher courses or pass new tests to keep their skills current.

The related verb is certify: “The mechanic was certified to work on hybrid engines.” The person or organization that grants certification is called a certifier or a certifying body.