10 Base T / 100 Base T Straight

10BaseT and 100BaseT are most common mode of LAN. You can use UTP category-5 cable for both mode. (You can use UTP category-3 cable for 10BaseT, in which there are only 3 wires inside the cable.)
A straight cable is used to connect a computer to a hub. You can use it to connect 2 hubs in the case one of the hub has an uplink port (and you use normal port on the other hub).

 

Pin ID side A side B
1 orange-white orange-white
2 orange orange
3 green-white green-white
4 blue blue
5 blue-white blue-white
6 green green
7 brown-white brown-white
8 brown brown

10 Base T / 100 Base T Cross

A cross cable for 10BaseT and 100BaseT is used to connect 2 computers directly (with ONLY the UTP cable). It is also used when you connect 2 hubs with a normal port on both hubs. (In other words, the cross cable is used relatively in a rare case.)

 

Pin ID side A side B
1 orange-white green-white
2 orange green
3 green-white orange-white
4 blue blue
5 blue-white blue-white
6 green orange
7 brown-white brown-white
8 brown brown