The two specifications discussed in this section are given the "privilege" of
being discussed first--like they care, right? 
--for an important reason. They are the
only specs that illustrate aspects of the performance of the hard disk in both fundamental
ways: positioning and transfer. As such, they are
very important to look for and understand. They certainly are not the only important
specifications, and there are some knowledgeable people who rank other metrics higher than
these, but few would dispute that they are essential enough that you should always look
for them on any hard disk you evaluate.
Next: Spindle Speed
