What does the add operation mean in the context of transaction execution with Fragment in Android?

The add operation in the context of transactions with Fragment in Android means adding a new fragment to a container (usually a ViewGroup) without removing or replacing existing fragments. The new fragment is overlaid on top of the current ones, and its interface becomes visible.

Example of usage:

FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
transaction.add(R.id.container, new MyFragment());
transaction.commit();

This differs from the replace operation, which removes all current fragments from the container and adds a new one. Add is useful when you need to overlay multiple fragments or keep previous ones in the stack.