The centromere is a chromosomal locus that regulates the proper pairing and segregation of the chromosomes during cell division. Despite their conserved, essential function, centromeres are characterized by the rapid evolution of both centromeric DNA and proteins. This book presents current views on centromere structure and identity. It deals with the epigenetic concept of centromere establishment and maintenance as well as with the role of DNA and centromeric transcripts in centromere formation and function. Special emphasis is placed on centromere evolution: different evolutionary models are discussed in detail and the latest research on the evolution of new centromeres and neocentromeres is presented.