Kleanthes Koniaris writes: Reading music is really all about memorization. You painfully learn how to look at a printed note (on paper) and immediately finger the instrument in the correct way. On a piano, each note lands on exactly one of the 88 keys, and this is fantastic. On a guitar, a given note could land on up to five separate strings, and you can always finger a lower fret and bend said strings, and so forth. So, it might not be unfair to say that you could find given note in perhaps fifteen distinct locations on a guitar neck---perhaps more! So, learning to navigate the guitar neck can be a real problem, and it is very important to keep the note names clear as one learns this complex layout.
The painful process of associating a symbol (graphical representation of a note) with a note (a tangible fret that you finger) is made much easier if you have a unique name to use to help you reason about note placement and memorization. This article describes the naming of notes, and how to keep track of them.