Distributed shared memory (DSM) allows nodes in a cluster to access shared memory across the network in addition to their local private memories. DSM uses a software memory manager on each node to map local memory into a shared virtual address space. It consists of nodes connected by high-speed communication and each node contains components for accessing the shared memory. Algorithms for DSM deal with distributing shared data across nodes to minimize latency and maintaining data coherence while minimizing overhead. DSM designs must consider the block size, shared memory space structure, and replacement strategy for local memory blocks.