Modern diagnostic ultrasound systems are essentially dedicated computers. As such, they are digital devices and use digital memory as their working memory.
Memory is where the ultrasound image is created in the system. Physically, it is comprised of a computer board containing memory chips, typically random access memory (RAM). However, as sonographers, it is easier for us to think of memory as a "memory matrix" comprised of a "checkerboard" arrangement of address locations.
The following three videos explain Memory, Memory resolution, and Contrast resolution: