Photos app missing - Want to migrate from iPhoto

Hi,

I would like to migrate my iPhoto Library from iPhoto App to Photos app (the new Mac app).

The thing is that back in the day I decided not to make the migration so I think I have lost the Photos app as I couldn't find it in the Applications folder.

I was looking to download it from the Internet but it seems it is something that comes with the OS.

What would be the best way to recover Photos app?

Thanks in advance