A work permit is a legal document permitting a foreign national to engage in employment while inside of Canada. Each year, Canada issues about half a million work permits to temporary foreign workers around the world. 

An open work permit is a work permit that is not job-specific. You may be eligible for an open work permit if for example you are an international student who graduated from a designated learning institution and are eligible for the PGWP or if you applied for permanent residence in Canada or if you are a dependent family member of someone who applied for permanent residence.

In each of these situations, you must meet additional criteria to be eligible.