With negotiation being an often difficult process involving complex problems, computer-based support has been employed in its various phases and tasks. This article provides a historical overview of software used to support negotiations, aid negotiators, and automate one or more negotiation activities. First, it presents several system classifications, including implemented models, system architectures, and configurations of various systems interacting with human negotiators. Then, it focuses on NSSs (negotiation support systems) and related systems introduced in the early 1980s and on ENSs (e-negotiation systems), which are deployed on the web. These broad categories are discussed from four perspectives: real-life applications, systems used in research and training, research results, and research frameworks.