What os came before unix?

Before Unix, several operating systems were in use, notably Multics, which was developed in the 1960s as a collaborative project between MIT, Bell Labs, and General Electric. Multics aimed to provide a secure and multi-user environment but was complex and resource-intensive. Unix was developed at Bell Labs in the late 1960s and early 1970s as a simpler alternative to Multics, focusing on portability and ease of use. Other earlier systems included CTSS (Compatible Time-Sharing System) and DOS (Disk Operating System) variants, which were primarily single-user systems.