Shake is cannabis flower that has naturally broken down through handling. It’s small parts that have come off of larger buds. For the average consumer, shake collects at the bottom of your stash, which you can also use to make joints. Convenience is the real benefit of shake—you can put it in a joint without having to grind it down. However, it is thought to be lower in quality.
If shake includes kief that also fell off of buds then the shake will likely be potent. Shake is usually of lower quality because it’s the last to go from your stash and has had the longest time to dry out and degrade.