RJ45 CAT5/UTP Ethernet Twisted-Pair Color Pairs (1-2 & 3-6)

RJ-45 Connector Standards

EIA/TIA 568B
RJ45 T568B Color Codes

Orange/White, Orange
Green/White, Blue
Blue/White, Green
Brown/White, Brown

RJ45 568B

EIA/TIA 568A
RJ45 T568A Color Codes

Green/White, Green
Orange/White, Blue
Blue/White, Orange
Brown/White, Brown

RJ45 568A

A crossover cable uses a 568B connection at one end, and a 568A at the other.
Normal patch cables have the same connection at both ends (I prefer 568B).
Keep in mind the images above show the RJ45 connectors with tab down!