1) A lease is a contractual agreement where a lessee pays a fee to a lessor to use an asset owned by the lessor. 2) There are different types of leases including operating leases, financial leases, sale-and-leaseback, leveraged leases, and capital leases. 3) When evaluating the lease versus buy decision for an asset, the key cash flows to consider are the lease payments, tax benefits of depreciation if buying, and potential debt displacement effects if leasing.