In order to learn about linking the site you need to understand the basic terminologies used in this perspective like Backlink, Inbound link, Outbound link, Reciprocal link and Link Exchange. I will explain each of these terms in a very simple way with examples.
Backlink:
Backlinking can be defined as putting a link of a site on other site. It serves as a vote for one’s site and increasing the number of votes results in an increase in the popularity of site. For example, if a site has a url www.abc.com and other has www.xyz.com and site “xyz” places the link of site “abc” then it is called backlink to the site "abc". Through this way , one may increase the site traffic as one site has been marketed by another site.But this will not happen in just a few days .Search engines will take some time to recognize those links.
Outbound Link:
If a site has a link to other sites then the link is called outbound link. The thing which is more important for SEO is that the site must contain quality outbound links. It means that if a site links to other sites and destination site is relevant then this will result in an increase in the page rank of the site and site gets higher positions in search engine result pages.
Inbound Link:
It is the reverse of outbound link and these are the links pointing to your site from other sites. Like quality outbound links, quality inbound links can also play an important role in receiving high ranks in search engine result pages.

Link Exchange:
Exchanging links is another way of building quality backlinks. In this type of linking ,two sites exchange links with each other .For example I find site B relevant to my site A and I placed site B link on my site A and requested site B to place the link of my site A . This is done by contacting the webmaster of sites and requesting link exchanges.But my advice will be to only exchange links with those sites that are relevant to your site , have a higher page rank and also have decent traffic floating to that site on daily basis.
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