INTERNAL LINKS are the best because if you ever change the URL for a site then you don't have to update all the link tags that referenced that URL, the site does it for you! Of course you can only use these to reference pages on our website, if it's to another site (like Facebook) you have to use an external link.
EXTERNAL LINKS will link out to anything if you put in the URL. You can even link to stuff on our site using the URL in an external link rather than linking to content through an internal link (which isn't ideal but you have to do it with things like blogs).
The easiest way to link to a particular blog is to know the blogs URL and use the EXTERNAL LINK option. There is no good way to use an INTERNAL LINK option. So you will need to remember to update the link in these links if you ever change it.
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