One way link building is a process of getting a link on another website without giving a link to that website. It is also known in the names of Link campaigns.
nbound links and backlinks, come under the umbrella term of 'Link building services' that refers to any hypertext link on an external website that links back to a page of your website.

One way links send a strong message to search engines that your website is so informative and interesting that other sites want to tell other people about it by placing the link of your website without expecting you to place a link of his website on your website.