Think of the dispatcher as the traffic cop who tells the requests which shared server to go to. The shared server is the process that does the work on behalf of the user. There are a limited number of shared servers in an MTS configuration and each is shared by all users using MTS. In a dedicated server environment each session that gets established gets one process on the server. There are advantages and advantages to using MTS; choose wisely. (Note: an instance can be configured with shared server and dedicated servers.)