Memory architecture refers to the design and organization of a computer's memory system, which includes various types of memory such as RAM, ROM, and cache. It determines how data is stored, accessed, and managed, impacting the overall performance and efficiency of a computer. Different memory architectures can include hierarchical structures, where faster memory types are used for immediate data access, while slower types store larger amounts of data. This organization helps balance speed and capacity, ensuring that the system operates effectively for various tasks and applications.