Citation Metrics measure the importance of a journal based on how often the articles within it are cited by other "important" journals. There are tactics to "game" this system, so only use this as one piece of information when judging journal quality.
Use this information to find top journals in a field to keep on top of the research, or to research publishing opportunities for yourself.
Common predatorial tactics
The "publish or perish" culture has turned scholars into prey, and the predators that have arisen out of this culture are publishers looking to cash in on our desire to have our research known. They learn how we research quality and adjust their tactics. Do not rely on years-old advice of how to spot predators - always be skeptical. Here are some of their recent tactics: