568A is a wiring standard setup by the
TIA/EIA. Part of it determines the order in which you place individual wires into an
RJ45 jack--an RJ45 looks just like a telephone jack (
RJ11), only bigger--when constructing a
twisted pair cable. When you get a roll of networking cable (as opposed to individual cables that are allready finished), it doesn't have jacks on each end. So, you cut off the amount that want, order the pairs of wires according to what type of cable you want, and
crimp them into an RJ45 jack to make the cable usable.
For 568A you put the pairs in this order (make sure the RJ45 jack is facing downward):
White/Green Green White/Orange Blue White/Blue Orange White/Brown Brown
When it says White/Orange or White/Green that means the wire is White with a green or orange stripe.