Something on your website (possibly a helpful article, useful software, or something entertaining), that people are likely to link to from their site. If someone finds some of your content valuable enough to link to it, you know that you are offering useful content, and building backlinks at the same time.
Links or hyperlinks are how the web is navigated. To move from one website to another, or from page to page on a website, users click on links. Links are created using an HTML anchor element. Every link generally has at least two properties; the destination URL, or where the user will be taken if they click on the link; and the anchor text, or the words on the page that are clickable to the user.
Links and linking play an important role in search marketing for a number of reasons. One reason is that search engines use the number of links from external websites (backlinks) as well as the anchor text contained in backlinks as part of their algorithm to determine the topic relevance and authority of a web page.
Long tail search terms are search phrases people use to find your website that contain your target search terms, but that have leading or trailing words, or both.
For example, your target term may be "widgets" - but people will likely find you by using a long tail terms like "new green widgets for sale."
If your website is well optimized for the search engines, when reviewing your web analytics you will see that although you get a lot of visits via searches on your primary target search terms, the majority of your visits will be from long tail search terms.