Attribution

Attribution just means crediting an author, as in a byline:

e.g. "...by Lowest Troll"

The Creative Commons consortium refers to parametric licenses that require attribution as "by-", so the "by-sa" license requires both attribution and share-alike terms. The GFDL license requires the five most prominent authors to be credited so it too has an attribution requirement.

Due to Wikimedia corruption and Mediawiki deficiencies (likely related) the Wikimedia usurpers do not recognize this legal requirement but instead rely on their GodKing's assertion that "everything is ok" and no legal trouble will result. That GodKing is not a lawyer, however, so this belief in his opinion is only groupthink, and probably quite dangerous.