This paper is a survey on the area of signature-based Gröbner basis algorithms that was initiated by Faugère's F5 algorithm in 2002. We explain the general ideas behind the usage of signatures. We show how to classify the various known variants by 3 different orderings. For this we give translations between different notations and show that besides notations many approaches are just the same. Moreover, we give a general description of how the idea of signatures is quite natural when performing the reduction process using linear algebra. This survey shall help to outline this field of active research. At the moment the area of signature-based Gröbner basis algorithms is confusing and vast. More and more papers are published proving statements already proven before, and even more publications can be found on "new" variants that boil down to be a known one just with a different notation. In this paper we try to give a rigorous survey on signature-based Gröbner basis theory, including all variants known up to now. We lay an emphasis on understanding and we show how the variants presented over the last years are mostly differ in small parts only. Moreover, we give the reader a vocabulary book at hand which helps to understand how notations, varying for different authors, coincide. Since this is a survey, we do not give proofs if they are long, complex, or do not help in understanding the topic. We always explain the idea behind the proofs and refer to the related publication which includes a complete proof. There the reader is then, with our descriptions and explanations, able to understand the