Anchors in canyoneering are what we attach ourselves to while descending a canyon so that we can safely rappel or down-climb with rope assistance. Not all anchors are created equally!
There are 4 different types of anchors:
Natural, Man-made, Retrievable, and "meat" anchors.
These consist of "natural" things found in the environment. Rocks, boulders, tree trunks, roots, etc. These are the preferred anchor of choice as we as a community is not bringing in gear which will permanent in the walls. These anchors have mostly stood the test of time. However, do not assume that just because it is attached to a tree, that it is safe! Every anchor needs to be examined before using it.
These anchors are the "permanent" type which are literally drilled into the rock. There are different types of these as they can consist of bolts, hangars and pitons. Beginners erronously put their trust in these over natural anchors at first because there is some notion that it is "safer". Some bolts have been securely fastened or glued into a work and has stood for decades. Other bolts have been drilled incorrectly, installed incorrectly, placed incorrectly, and not glued-in correctly. There have been some stories of where bolts have failed (typically because they fall into the aforementioned reasons)! Do not assume that just because it is attached to the rock, that is safe! Every anchor needs to be examined before using it!
This type of anchor is deployed around a technique called "Ghosting". That means to leave no evidence of your descent, including webbing and anchors. There are ways to tie anchors around natural and man-made anchors so that you can retrieve your anchor after everyone is done rappelling. One must needs to be proficient with technical rope work before deploying this, otherwise you could get a rope stuck (and someone needs to climb UP the rope to get it unstuck) which may have disastrous results for your party! This is NOT taught on Canyoneering101.com
A meat anchor refers to when we use our literally bodies as a counter-weight to the rappeler or down-climber. We do this when no natural or man-made anchors are to be found or used! Extreme caution must be used as bodily injury or death may result if not properly used or deployed. Generally there should be more than one-person on a "meat" anchor when a person is rappelling. The last person down will not have the assistance of a "meat" anchor and so the people at the bottom must have a way of "capturing" them. This is NOT taught on Canyoneering101.com