In this thesis color-kinematics duality will be investigated. This duality is a statement aboutthe kinematical dependence of a scattering amplitude in Yang-Mills gauge theories obeyinggroup theoretical relations similar to that of the color gauge group. The major consequenceof this duality is that gravity amplitudes can be related to a certain double copy of gaugetheory amplitudes. The main focus of this thesis will be on exploring the foundations ofcolor-kinematics duality and its consequences. It will be shown how color-kinematics dualitycan be made manifest at the one-loop level for rational amplitudes. A Lagrangian-basedargument will be given for the validity of the double copy construction for these amplitudesincluding explicit examples at four points. Secondly, it will be studied how color-kinematicsduality can be used to improve powercounting in gravity theories. To this end the dualitywill be reformulated in terms of linear maps. It will be shown as an example how this canbe used to derive the large BCFW shift behavior of a gravity integrand constructed throughthe duality to any loop order up to subtleties inherent to the duality that will be addressed.As will become clear the duality implies massive cancellations with respect to the usualpowercounting of Feynman graphs indicating that gravity theories are much better behavedthan navely expected. As another example the linear map approach will be used to investigatethe question of UV-niteness of N = 8 supergravity and it will be seen that the amount ofcancellations depends on the exact implementation of the duality at loop level. Lastly, colorkinematicsduality will be considered from a Feynman-graph perspective reproducing some ofthe results of the earlier chapters thus giving non-trivial evidence for the duality at the looplevel from a dierent perspective
