a) The time required to receive valid data from a memory device following a read signal. b) This is the time it takes from when a disk command is sent until the disk reaches the data sector requested. Access time is a combination of latency, seek time, and the time it takes for the command to be issued. Access time is important in data intensive situations like hard disk recording, multimedia playback, and digital video applications.

Lower access times are better. Keeping your drives in good shape with periodic de-fragging, etc. will ensure that your drive is providing the fastest access times it can.