Impact Factor: What this really means?

--> Every journal has its own impact factor (as stated by ISI ratings), but I observed, some of the resource people (with all respect to them) here in this website have mentioned an impact factor in their own profile page. What does this really signify?

--> Is that the number of citations that you got for your article or simply you have mentioned the impact factor of the journal in which you have published?

--> Kindly share your views and expert opinions.