How are individuals officially nominated as candidates for corporate board seats?

Does this occur prior to the next annual general meeting (AGM)?

I believe some companies have a nominations committee, typically comprising the board chair, vice-chair, board members etc. Do institutional investors with enough voting influence proffer names, does the nominations committee hire an outside company to present their recommendations, does the board tend to just submit their names again etc?

I understand that the nominations committee presents the initial nominees to the membership at the next available AGM, then there is a call for any further nominations from among the members present (sometimes a total of three times).

Do the proposed nominees have to be present?

Unclear as to how this process works.

I suppose, in the event of the founder also serving as both chairperson and CEO, they can just bypass the usual processes.