My SEO e-Guide by Nicolas Gremion - HTML preview

5. Anchor Text

Anchor text is the clickable text that is associated with a link. Google looks at the anchor text, freshness of the anchor text and changes to the anchor text over time.

• If there is a disparity between the anchor text and the document that it links to, possibly due to changes in domain ownership, Google could look at the time this occurred and ignore all the valuable links to your document prior to this event.
• Let people link to you with appropriate anchor text.

Unique Words, Bigrams, Phrases in Anchor Text

Google analyses the unique words, bigrams (pairs of letters, words or syllables) and phrases in anchor text for a document.

• Google analyzes graphs of unique words, bigrams, and phrases in anchor text to see if this information is real. Results that are created artificially would show spiky graphs whilst natural data would show organic graphs.
• Don't try and SPAM the search engine using unscrupulous link trading or search companies as you could get black-listed and not recover from a lowered ranking.