What is a family tree?
It is simple chart showing family relationships in a tree
structure, at it is usual genealogy and medicine but of course
can be used for private historical purposes and many other. Family trees are typically represented with the oldest generations at the top and with the newer generations at bottom. There are many different themes of a tree, it can be used to determine all descendants of a single person or it might include all relatives with the same surname which is the same as showing all male descendants in a tree.
Cousin is a term that represent relatives with whom one share ancestors, but today it is usually used to describe the relationship e.g. brother, sister, uncle, etc. Cousin chart is somehow similar to family tree, it is used to determine degree of cousin relationship between two or more individuals, but it is not represented as a tree chart, but a simple table.
The name of cousinship is determinate by generation level and individuals closely related to same ancestors, and cousinship starts with closes relatives, like brother or sister, uncle, etc.
The longest family tree in the world until today is tree of a Chinese educator Confucius (551-479 BC) and it has more then 2 million members, that is around 80 generations of relatives, and it spreading every day.
Internet made searching for your relatives extremely easy, there are numerous sites on web that are offering database of people and their relatives, and with few clicks online you can find out who is your ancestor and where do they live, and even make contact with them.