In Unix all normal files are Hardlinks. Hardlinks in a Unix (and most (all?) ) filesystems are references to what's called an inode. The inode has a reference counter, when you have one "link" to the file (which is the normal modus operandi) the counter is 1. When you create a second, third, fourth, etc link, the counter is incremented (increased ) each time by one. When you delete (rm) a link the counter is decremented ( reduced ) by one. If the link counter reaches 0 the filesystem removes the inode and marks the space as available for use.
In short, as long as you do not delete the last link the file will remain.