The document discusses three Google algorithms: Panda, Penguin, and Hummingbird. Panda was introduced in 2011 to give more weight to original content over copied content. Penguin was introduced in 2012 to punish websites using manipulative or spammy link building practices. Hummingbird was introduced in 2013 and incorporated elements of Panda and Penguin while also focusing on returning mobile-friendly search results.
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