The purpose of this paper is to introduce readers the concepts and ideas that are related to modals and auxiliaries on the basis of cognitive grammar. During my research, in some exceptional cases I will employ the ideas of traditional grammar as well. In the case of modals, there are a lot of ideas which divide linguists into more groups. There were a lot of studies made on modality, but there were not any papers that were accepted among everybody. This can be mainly due to the complexity of the topic. In this paper I will try to mix the ideas of different linguists and I intend to make a whole research on this topic.