Effective Character Level
The Effective Character Level is a concept from D&D 3.5 which specifies the effective level of a player character with no class levels assigned. For most playable races, this is always ±0, but some advanced races may have adjustments of +1 or even higher based on the strength of their racial abilities.
If a character has ECL+1, then they are considered to be first level even without any actual class levels assigned. If a character with ECL+1 has one level of a class, then that character is considered to be 2nd level; in order to reach 2nd level in that class, the character must acquire the experience points normally required for 3rd level.
Difference from Pathfinder: Pathfinder has no concept of ECL; however, there is some similar discussion about "standard", "advanced", and "monstrous" races in the Advanced Race Guide. Refer to the text of the Race Builder chapter for more details.