What are tag-along and drag-along rights in a private company shareholders' agreement, and whom do they protect?

Both govern share transfers when a majority/large holder sells. A tag-along (co-sale) right protects minority shareholders: if a majority holder sells to a third party, the minority can 'tag' onto the sale and sell their shares on the same terms and price — so they aren't left behind with a new, unknown controlling owner and can share in the exit. A drag-along right protects the majority/buyer: if a holder above a defined threshold agrees to sell to a third party, it can 'drag' the minority into selling too, on the same terms — enabling a clean 100% sale that a buyer typically demands, preventing a small minority from blocking an exit. They're two sides of the same coin: tag is a minority protection, drag is a majority/exit-facilitation tool. In PE this matters a lot — sponsors insist on drag rights to guarantee they can deliver a full exit, while management/minority holders negotiate tag rights and fair-terms protections (e.g., that drag must be at a bona fide arm's-length price).