Any power tool from the reputed and established manufacturers, Dewalt comes with a model number same goes for Dewalt Drills. In the Dewalt model number the first three letters signify the family of similar models, it belongs from.  For example, in the case of DCD771, the DCD stands for Dewalt Cordless Drills, and the three-digit number that follows it in this case 771 is the model number. Sometimes this is also followed by the letter 'N' which stands for 'tool body' only offering.