Music Technicalities

Are there any recommended or required stipulations as to the frequency of music in our ages? What I mean by this is: does it have to be 44, 96, 128 etc khz? Is the only requirement that it be in the OGG format? If not, what are the major advantages of using a lower frequency? I would think that it could/might improve performance - but by how much? Is it even something to concern myself with?