Why do links and social media icons in footer widgets not link correctly

When I add html tags in the footer widgets of websites on my network, the tags always link only to the current page regardless of where the link points. For example if I do a tag <a href="externalsite.com">link text</a> and I am on mypage.com/home, when I click the link it stays on mypage.com/home, and does not link to the external site. I am also having trouble with social media widgets in the footer widgets not linking correctly, with similar results. For example, instead of going to pinterest.com/mysite, the Pinterest icon links to mysite.com/pinterest.com/mysite. Thanks for any suggestions.