General overview of links
Links into a site (it's back links) should bring visitors (traffic), a link is effectively an ‘advert' for a site, and they also play a part in ranking the website within search engine result pages.
Generally, big brand sites ignored, search engines are responsible for bringing the majority of visitors to a website so ranking well within these results (known as organic search results) is desirable.
Links out of a site provide further avenues of information to visitors and as such can prove of use or value. It depends on the overall value of a website as to whether visitors will want to return and on the overall appearance as to whether they will stay. Too many links out or even unattractively presented links can prove detrimental and simply turn visitors away.