Parts of a Crossbow String
The serving area of a crossbow string is the middle section of the string. This is where the bolt will be nocked or resting against when the crossbow is cocked.
On the ends of the string for a recurve bow you will find two loops. These loops are to be placed over the limb tips so that the string can be attached to the crossbow. On a compound crossbow, the end loops wrap around the cams which are located on both limbs. Note, for compound crossbow you require a crossbow/bow press to change or remove the strings.
These are added to the crossbow string to effectively reduce string noise when the crossbow is fired. Usually made of felt, you would mount two of them to either side of the string closest to the limbs and are held in place by the tension of the string.