These links are definitely useful ones but it would have been better if you had posted some description and information too. SEO is an important task to be taken care of these days, so perfect knowledge should be there to people as per their requirements.
SEO(Search Engine Optimization) is the technique(or set of techniques) used to improve the visibility of a website in Google search engine. It can be on page or off page. Various methods are used to promote a website, one of such method is SEO. In simple terms you can say that Search Marketing including PPC and SEO make up a small part of digital marketing.
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