If your cofounder is like your spouse, then your board members are like your mother-in-law and father-in-law. You are going to see them regularly, they are hard to get rid of, and they can have an enormous impact on your company’s future.
The members of your board are among the most important people you will ever “hire” for the company. The best board members will play key roles in company strategy; sourcing, hiring, and closing senior executives and key hires; fundraising; operations; and governance. In mid-stage companies, they are often responsible for selecting/keeping/firing the CEO, and then holding that person accountable for deadlines, plans, and deliverables. Later in the life of a company, board members play more specialized roles through the various committees they may be part of. (I won’t cover public boards here.)
Your board will typically be composed of a few key players: VCs who invested in your company, independent board members, and members of the founding team (aka “common seats,” which usually include one or two founders, or rarely as many as three). If you have an external, non-founder CEO, he or she will also have a board seat (and in some cases an external non-founder COO will as well).