Something somebody made up tons of years ago. Something that's just there to make other people feel less important, beautiful, and more nerdy and dorkish than the so called, "popular people." A word that makes everybody else sad except for the ones that are actual popular.
As the word suggests, this describes how popular one is on the internet. E-Popularity is common in online forums and is based simply on how many posts you have and how many people (or fan girls) respect you. The higher your e-popularity is, the more likely you're going to win any argument... whether you're right or wrong. Also, if your e-popularity is high enough, you may even become a mod or assistant admin. Some people create websites and forums simply to increase their e-popularity. Most attempts turn out unsuccessful.
animeking: OMG, KoolKid203847 has e-popularity through the roof!