In biology, Pedigree chart is reffered a
record especially of a purebred animal.In humans , A pedigree chart is a visual representation of a particular trait among members of an extended family. The family usually includes at least 3 generations (most pedigrees have many more). Squares represent males, and circles are used for females. If an individual has the trait, his shape is darkened.
Pedigree analysis can be used to determine the mode of inheritance for a particular trait. If you have enough info, you can figure out if the trait is recessive, dominant, X-linked, etc. However, it tells you nothing about the alleles that lead to that particular trait. Sometimes it can be difficult to determine mode of inheritance, as not all the data may be available !!