In the context of UK immigration, a Certificate of Sponsorship
(CoS) is a document issued by licensed sponsors to enable skilled workers to apply for a Tier 2 (General) visa. Employers who are licensed sponsors can assign a CoS to prospective employees from outside the European Economic Area (EEA) and Switzerland. The CoS contains details about the job, the individual's personal information, and the sponsor's information. It plays a crucial role in the visa application process, as applicants need a valid CoS to apply for a Tier 2 visa to work in the UK.