In order to balance out the racial advantages of some non-human races that
can be played as PCs, a level adjustment is added to their actual level in
order to determine their Effective Character Level (ECL). In calculations
determining their level advancement, this ECL is employed in place of their
actual level. Thus consider a just-created full-blooded Drow wizard, level
1. Drow are a powerful race and have a level adjustment of 5. As a
consequence, this first level wizard starts with the experience points of a
5th level wizard, and must gain the experience points normally required to
attain sixth level in order to realize the advantages that normally accrue to
a second-level wizard. The level adjustment is static and decided by the PCs
race; consequently, this Drow wizard will require the experience of a level
50 PC in order to attain level 45, and once they reach that point they will
be unable to progress further - as if they had reached level 50 (because, in
effect, they have - their ECL is now 50).
* This DOES make it harder to start a PC of a race with a large level
adjustment. It also prevents them from topping out at a point where they are
far more powerful than others PCs of their level and guild.