A "证书" (Certificate) is an official document that verifies a person's qualifications, achievements, or completion of a specific course or training. It is often issued by educational institutions, professional organizations, or government bodies to acknowledge skills or knowledge in a particular area. Certificates can be used for various purposes, such as applying for jobs, furthering education, or demonstrating proficiency in a skill. Common types of certificates include 学位证书 (degree certificates), 职业资格证书 (professional qualification certificates), and 培训证书 (training certificates). They serve as proof of a person's capabilities and accomplishments.