One of the hardest things to sort out in law school is whether to choose a litigation or transactional career. Law school training (at least the required part) is notoriously biased in favor of litigation, so the burden is on law students to figure out whether they want to default into a litigation career or seek out training for a transactional practice.
By the way, you are forgiven if you are a law student and don't even know what a transactional practice is. (And when transactional work is slow at law firms, as is the case on a fairly cyclical basis, even first-year lawyers walk the halls asking themselves, "What's a 'deal' anyway?") Prof. Kenneth Klee has written a great paper on transactional law, and you can also check out Columbia Law School's transactional program (arguably the best around) to get a sense of what's involved.
Note, too, that transactional work can get very specialized. For example, my old law firm (Irell & Manella) has sub-groups focusing on art transactions, intellectual property transactions, and IPOs and private placements (among others).