The subject of representation theory originally arose from the study of symmetries on certain spaces. It has long been known that many two-dimensional geometric phenomena have algebraic explanations via the subject of representation theory. In the last fifteen years it has been conjectured that analogous explanations for problems ins three-dimensional geometry should raise from introducing so-called higher symmetries, giving rise to the subject of 2-representation theory, or categorification. This is the newly developing research area where this proposal is situated.The proposal has two main objectives:In her previous Marie Curie fellowship the applicant and her co-author have made significant progress on the representation theory of general linear groups over a field of positive characteristic by developing higher categorical methods to iteratively generate categories of representation for the general linear group of rank two. This yields very strong results on the categories of representations in this case, such as e.g. multi-gradings and braid group actions on their derived categories. The first aim of this proposal is to generalise these concepts to general linear groups of larger rank.The second objective investigates affine Hecke algebras, the applicant's main area of expertise prior to her Marie Curie fellowship, in the context of categorification. It applies newly developed concepts to algebras defined by Khovanov-Lauda-Rouquier and Varagnolo-Vasserot, which are known to have very similar representation theory to affine Hecke algebras of different types. The goal of this part of the project is to gain a thorough understanding of the homological structures of these algebras.