Capital budgeting refers to the long-term planning process used to evaluate proposed major investments and capital expenditures. It involves evaluating potential capital projects and determining which projects to invest in. The key methods used to evaluate projects include payback period, net present value, internal rate of return, and profitability index. Payback period is a simple and widely used traditional method that measures the time required for the cash inflows from a project to repay the initial cash outlay. However, it ignores cash flows beyond the payback period. More sophisticated discounted cash flow methods like net present value and internal rate of return are better as they consider the timing of all cash flows and investment cost of capital.