Individual call and text tones can be set for contacts so it’s easy to know who’s getting in contact without having to physically look.
From Contacts, go to the contact entry and tap Edit. Scroll down until you reach the Ringtone or Text Tone option.
Tap on either and choose a new tone for that contact. Tap Done and that person will now have their own unique tone.
You can also jump straight to the Tone Store, or opt to Download All Purchased Tones from this sub-menu.