A certificate is a document for authentication of something. It may be an award that can be given to people. The certificate can be given to people for graduation, for good working skills, or to thank someone who has done good things. They are usually tied to an occupation, technology, or industry. Certifications are usually offered by a professional organization or a company that specializes in a particular field or technology. A certification demonstrates that the person have a specific skill or level of knowledge, ultimately showing an employer that person know what need to do to successfully perform a job. Other items, such as patches, badges, lapel pins, watches, and medals can also come with the certificate.
Many other kinds exist. A certificate of authenticity says a thing is real. For example, it can say that a painting was made at a particular time by a particular artist and is not a forgery. A certificate of occupancy says a building is fit for use. A certificate of deposit says someone has money in a bank. A birth certificate is one of the kinds of vital record.