1. Google purchased YouTube for $1.65 billion in October 2006 (Burgess and Green 1; Sorkin and Peters).
2. YouTube tends to change its features somewhat frequently. For example, for the first few years it used a “star” rating system, in which people could rate videos from 1 star (“Poor”) to 5 stars (“Awesome!”). In 2010, this was replaced by a simple thumbs up (like) or thumbs down (dislike) metric (Kincaid). The rationale was that people tended to rate videos with 5 stars, and sometimes 1 star, but very few in between (YouTube Blog). The bulk of the discussion, unless otherwise noted, refers to YouTube as it appeared during the majority of the fieldwork period, 2006-2008.