If I want to include an image within a news or forum post, what is the best way to do that?  I'm talking about referencing or linking to an existing image in a gallery, for example, not uploading or inserting via the post.  For example, if I have an image in my personal gallery and I want to show a thumbnail image of that in a news post, what's the best way to do that?

I've searched for a possible answer but can't seem to find one.

Thanks in advance for your help!

Edit:  nevermind   I just discovered that if you go to edit an image you will see the URL within the Image setting.  You can use that URL inside of an "img" or "thumb" tag to display the image.  Pretty straight-forward really...but I was having a difficult time trying to find a valid reference to the image.  All figured out now   Hope this helps someone else who may be experiencing the same challenge.
 

Right, it'd work as per your solution under 'Edit:'.

In my mind the best way is to upload to the File/Media Library first, then add to the gallery referencing that, and add to the other content referencing that also.
That way the image file is an independent content entity in it's own right and you aren't creating a cross-dependency.

That said that is all probably unnecessary hassle for most people.