According to the History Learning Site of the United Kingdom, the main part of a coat of arms was the achievement and it included the crest as one of its eight parts. In this definition, the crest was the shield attached to the chest. The supporters were pictures of beasts of humans that appeared to hold up the crest. On top of the shield was the helmet, which indicated the rank of the person.
The mantling was simply a piece of cloth that draped down from the helmet. This cloth was meant to shield the wearer's eyes from the sun. On a family coat of arms, this can be many colors. The wreath connected the crest to the helmet. Coronets are like crowns and what are normally seen at the tops of a coat of arms. A motto, which could be a war cry or family saying, was placed at the bottom of the shield.
Contrary to popular belief, family crests were actually only granted to a single person, usually a knight, who actually chose the components. Since families were proud of the knight's bravery or achievement, these became symbols of the knight's entire family. These crests were passed down from generation to generation. In the 21st century, many people who are exploring their history try to find their family's crest as a way of knowing the origin of their family.
There is conflicting information as to what the crest is and what the components are. Going a step further, some genealogists dispute the accuracy of family crests and their components. For example, some websites say "the crest" is simply the beast that is located on the coat of arms. Others call the coat of arms "the crest." The website ProGenelalogists.com says that except for a few, there really is no coat of arms for most surnames. However, many websites have been developed that allow users to search for their surname to see a depiction of their crests, or coat of arms. Some of them may even show two different crests with different components for the same surname.