There is much discussion in these last few months about reciprocal linking. In the last Google update, reciprocal links were one of the targets of the search engine's latest filter. Many webmasters had agreed upon reciprocal link exchanges, in order to boost their site's rankings with the sheer number of inbound links. In a link exchange, one webmaster places a link on his website that points to another webmasters website, and vice versa. Many of these links were simply not relevant, and were just discounted. So while the irrelevant inbound link was ignored, the outbound links still got counted, diluting the relevancy score of many websites. This caused a great many websites to drop off the Google map.
The SEO starter guide describes much of what your SEO will do for you. Although you don't need to know this guide well yourself if you're hiring a professional to do the work for you, it is useful to be familiar with these techniques, so that you can be aware if an SEO wants to use a technique that is not recommended or, worse, strongly discouraged.
What's the authority of your website or webpage, or any other page on the internet for that matter where you're attempting to gain visibility? Authority is an important component of trust, and it relies heavily on quality links coming from websites that Google already trusts. Authority largely relates to the off-page optimization discipline of SEO that occurs away from the webpage as opposed to the on-page optimization that occurs directly on the webpage.

Page and Brin's theory is that the most important pages on the Internet are the pages with the most links leading to them. PageRank thinks of links as votes, where a page linking to another page is casting a vote. The idea comes from academia, where citation counts are used to find the importance of researchers and research. The more often a particular paper is cited by other papers, the more important that paper is deemed. 
A breadcrumb is a row of internal links at the top or bottom of the page that allows visitors to quickly navigate back to a previous section or the root page. Many breadcrumbs have the most general page (usually the root page) as the first, leftmost link and list the more specific sections out to the right. We recommend using breadcrumb structured data markup28 when showing breadcrumbs.

Search Engine Optimization