This is usually a folder inside your project's root folder

Usually the main path where the projects are located can be found in Preferences > Projects Folder

Mandar, please do not trust/rely on the auto generated backup files. Create your own in step 5, export project. The generated iwzip files are reliable and complete (unlike the built in backups)

this is in response to your post, of course as suggested by Esahc if you export the fine .iwzip (I only use this method) it is much safer.