Capital budgeting is the planning process used to determine if long-term investments or capital expenditures are worth pursuing. It involves analyzing potential capital projects to see if they will provide returns that exceed their costs. There are three main types of capital budgeting decisions: accept/reject decisions that determine if a project's returns are higher than costs; mutually exclusive decisions where only one of several competing projects can be chosen; and capital rationing decisions that rank projects when funds are limited and the most profitable must be selected.