Memory Type: DDR3 PC3-12800, DDR3 (non-ECC)
Maximum Memory: 16GB
Slots: 2
13" system processors:
2.5GHz Dual Core Intel Core i5 or 2.9GHz Dual Core Intel Core i7 processor.
15" system processors:
2.3GHz Quad Core Intel Core i7, 2.6GHz Quad Core Intel Core i7, or 2.7GHz Intel Core i7 processor.
Memory or DRAM is the "working" memory of the computer. It's used to store data for programs (sequences of instructions) on a temporary basis.
video - installing memory