What are advantages and disadvantages of internal and external recriuitment?

What are advantages and disadvantages of internal and external recriuitment?
Internal - cheaper option may not be so cheap given the time involved to find employees. Just running ads and using job boards do not get you the best candidates. Harder for internal recruiters to source candidates, cold call and get referrals of top applicants from outside the current employee referrals.

External Recruiters have a vested interest to get the company the best candidates b/c they want those candidates to stay a long time so they can continue to do business with them esp as the placed candidate moves up and hires more people. They also want to get paid so they have to find the best candidates. Might seem pricey to pay a fee, but you are only as good as your people and you also do not need to hire teams of expensive internal recruiters.