A general transcription factor that plays a major role in the activation of eukaryotic genes transcribed by RNA POLYMERASES. It binds specifically to the TATA BOX promoter element, which lies close to the position of transcription initiation in RNA transcribed by RNA POLYMERASE II. Although considered a principal component of TRANSCRIPTION FACTOR TFIID it also takes part in general transcription factor complexes involved in RNA POLYMERASE I and RNA POLYMERASE III transcription.