ability score increase:
Your Intelligence score increases by 1.
age:
Tieflings mature at the same rate as humans but live a few years longer.
alignment:
Tieflings might not have an innate tendency toward evil, but many of them end up there. Evil or not, an independent nature inclines many tieflings toward a chaotic alignment.
Size:
Medium
speed:
Your base walking speed is 30 feet.
Languages:
You can speak, read, and write Common and Infernal.