Electronic – What do memory configurations like “256Kx18” mean

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This is a beginner question here. When choosing memory ICs, one of the options is the memory size/configurations. I understand the size part, but what does the "16Kx9" mean? It seems the same memory size is usually available in different configurations. I attached a screenshot from Digikey as an example.

example

Best Answer

256K x 8 means 256 kibi-locations, each location holding 8 bits. There are 18 address lines (218 = 256 * 1024) and 8 data lines.