Which SEO tricks Google consider as spam?

[shreeharisg]

Give numbers of tricks that will consider Google as spam and it will harm our Google search engine ranking.
Many bad SEO tricks can give bad effect on website Google search engine rank.

[todion]

Hidden text, Clacking, nude link and non-relevant content always consider as spam in Google eyes.

[shreeharisg]

I don't think nude link. But I agree for other.;) Give any other trick which harm us.

[akshitasingh426]

Duplicate Content Submit
Take Many Back link from one website

[Fli]

maybe forum signature links. on Google its mentioned as technique where one tries to manipulate site ranking. here is more (https://support.google.com/webmasters/answer/66356?hl=en)

[seojesica]

In my opinion Duplicate content and over optimization are harmful for website.

[bind]

Alright above, cloaking and orphan pages also consider as spam in the eyes of search engine also creating more and more number of link for same Anchor text is also spam and given negative signal for your website.

[Fli]

creating more and more number of link for same Anchor text is also spam and given negative signal for your website.
im also afraid of this, i think google really watching this and puts this into consideration whether inbound links are organic (good) or built to enhance/manipulate site ranking on google (bad)