Conference on Living Together: Planets, Host Stars and Binaries, Litomysl, Czech Republic, 8 - 12 September 2014, vol.496, pp.114-117
Period changes in contact binaries obtained by the analysis of times of eclipse are often found to be chaotic in nature. However, they may be representable by a few cyclic changes superposed on a secular change. The cyclic changes are most likely caused by third components revolving around the contact binaries. This contribution shows some typical examples of the period changes in contact binaries.