AnimalTFDB predicted three kinds of factors that involve in transcription process including transcription factors (TFs), transcription co-factors and chromatin remodeling factors. According to the conserved DNA-binding domain (DBD), the TFs were classified into 71 families and a class named "Others" which includes some orphan TFs. Among them, the DBD 3D structures of 60 families have been demonstrated and we used those 3D images as logos for families. For the other 12 families whose 3D structures are unknown, we just put a blank picture on the family position. In addition, we merged the 72 families into 6 groups according to TRANSFAC database and huge literature work. The detailed relations between families and groups were showed on the left treeview. Transcription co-factors and chromatin remodeling factors were gotten by the GO items and were not classified into different families because they didn't have conserved protein domains.