XP?

Experience can also be taken away. All experience is tied directly to the submission you earned it from. If one of your submissions is deleted for rule-breaking, the experience associated with it is taken as well.

For example, if you have a project that has earned you 300 exp and it is deleted, you will lose exactly 300 exp.

Rules 'N Stuff

official-site-rules-t1040.html
submission-guidelines-updated-november-24th-2012-t40929.html

It is just the amount of influence on the site you have had.
You get it by posting submissions such as Projects, Skins, Mods, ECT.
There is a perk at level 10 that allows you on the whitelisted PMC server as well.

For a citation of this go here.
http://www.planetminecraft.com/members/levels/

xp gets you higher levels, and makes you happy


<- yay

XP and Leveling is to show your contribution to PMC.

XP is the leveling system of PMC, you gain absolutely nothing from it, other than maybe respect in the community. You can obtain said XP by posting quality submissions on PMC, Skins, Mods, Maps, Blogs, Texture Packs, etc..

ThursdayYou get it by Uploading various things, diamonds, downloads, etc..
XP Gains you Levels!
Levels can (sometimes) give you a bit more respect on forums! [NOT GURANTEED]

What he said.

You get it by Uploading various things, diamonds, downloads, etc..
XP Gains you Levels!
Levels can (sometimes) give you a bit more respect on forums! [NOT GURANTEED]
Also its cool to be the high level kid
Unlike
me.
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Xp is an award for posting skins, projects, texture packs, and blogs. Remember to put effort in your skins/projects/texture packs/blogs