SIMMs come in two flavors: 30-pin or 72-pin edge connectors. SIMMS also come in different capacities including 256K, 1MB, 2MB, 4MB, 8MB, and 16MB, to name a few.
SIMMs enjoy the same advantages as SIPPs. However, the SIMM is a newer technology and is more popular. SIMMs are easier to install than SIPPs. Most PCs today use SIMMs.