Lip-reading or the process of visual recognition of speech is a way to distinguish speech from the movements of the speaker's lips. In recent years, the interest in automatic lip-reading has been increasing and a lot of researches have been done in this field and it is still a leading research topic. This paper provides an overview of researches in automatic lip-reading. A list of used databases in the researches is provided with specifications such as number of speakers, speech content and image quality. In this article, various lip-reading researches are reviewed from recognizing numbers, letters, words and sentences, and traditional methods of feature extraction and classification to the new methods based on deep learning. In addition, Persian lip-reading activities include provided databases and related researches are introduced more comprehensively.