The startup file (startup.blend) is loaded at Blender startup. It contains the default startup scene and can be customized. Use this tags for questions about the startup file.
The manual entry for Startup File in Defaults
The Startup File stores the scene, Workspaces and interface which is displayed at startup and when loading a new file (File ‣ New).
You can modify and save your own customized startup file.
Use this tags for questions about the startup file.