Now we will understand each stage
Working Directory is the main directory that is initialised as Git Repository in which you put your file and edit the data or the extracted repository pulled from GitHub Server. This basically contains the file that you are consistently modifying or editing or creating new files. The changes you do in Working Directory doesn’t affect the changes stored in Git repository until these are passed into other two area.
In corollary, the stagged area is compared, with the beginning of the University session. As you admitted to university you have to register your information one time so that all another process such as marks you scored, the position achieved can be allotted to the particular person, that is you. Similarly, when you create a new file, you need to register that file in the index (if you are an android programmer you can consider it a manifest file). The file added to the index is called as a staged file.