Data is fetched from memory using the load instruction (LOD in the CSC-1). Conversely data is stored to memory using the store instruction (STD in the CSC-1). However, a computer that provides only these two instructions will be very limited and may not be able to implement any high level language.

In order to provide flexibility, indirect addressing allows the address to be created at run-time, often by adding two other numbers together. LOD and STD specify the address in the instruction itself, so the address can't be changed (unless the instruction is changed, which is possible but highly frowned on these days).

Most high level language data structures, such as arrays, records (structs), objects, linked lists, etc., require indirect addressing because the addresses cannot be known ahead of time and stuck into a LOD instruction.