recruitment

[Anver]

if a company has a job vacancy does it have to advertise externally

[scoobydooby]

No. Most companies will advertise internally, in the first instance, if they feel the post could be filled by someone already within the organisation. However, most will also accept applications from external candidates if they get to hear about the post (for example, if you had a friend that worked there and told you about it). It's cheaper to advertise internally.