How does RewriteBase work in .htaccess

I have seen this in a few .htaccess examples

RewriteBase /

It appears to be somewhat similar in functionality to the <base href=""> of HTML.

I believe it may automatically prepend its value to the beginning of RewriteRule statements (possibly ones without a leading slash)?

I could not get it to work properly. I think it's use could come in very handy for site portability, as I often have a development server which is different to a production one. My current method leaves me deleting portions out of my RewriteRule statements.

Can anyone explain to me briefly how to implement it?

Thanks