The document discusses different addressing modes used in computer instructions. It describes 10 addressing modes including implied, immediate, register direct, register indirect, auto-increment/decrement, direct, indirect, relative, indexed, and base register modes. It explains how each mode specifies the location of operands and gives examples. Addressing modes allow versatility in programming by enabling features like pointers, loop counters, data indexing, and program relocation while reducing the number of bits in instruction addresses.