It is a type of work permit that enables you to enter a foreign country and work there for a particular period of time. Without a work visa, you cannot work in a foreign country. Different countries may have different procedures and criteria for issuing work permit visas. Work permit visas are issued either on a temporary or permanent basis.
A temporary work visa remains valid for a particular period of time after which the visa holder needs to renew if his employer wants to extend his (employee’s) stay.