What is the Sum-of-the-Years Digits Method of depreciation and what is the reasoning for using the method, as opposed to standard depreciation?

The Sum-of-the-Years Digits (SYD) is an accelerated method for calculating depreciation. In most cases, assets are depreciated evenly over the useful life of the asset. However, SYD allocates the highest depreciation expense in the first year and the lowest in the last year. The reasoning is that an asset is most useful in the first years of its useful life. Picture the purchase of a new car, where the value drops quickest in the first year or two of ownership.