When compound bows were first developed, they included a small plastic rest that was glued just above the shelf. However, the designs of these rests have greatly improved, as modern bows are designed so that a specific type of rest can be bolted directly to the riser.
The two most common of these are the drop away rest and the full containment rest, where the Whisker Biscuit is the most popular manufacturer of this particular type of rest.
However, it is important to note that most analysts have determined that there are clear advantages in using one type of rest over the other. For example, many feel that the drop away option gives greater speed and accuracy. However, the whisker biscuit is much more reliable, especially in the field. So, who do you choose? A look at the specific types of rest themselves is a good place to begin.