cat > $FILE_NAME << EOF - Explanation of the inner workings

Question

I know what this one does, I learned "pattern like" and just works.

I also know:

• that > is a redirect to a file
• that << is also a redirect to file see below
• EOF is just a placeholder, when detected the file is closed

Can someone explain the inner workings of those instructions? Why does that work ?

Correction: the use of ´<<` is described in the man page of bash as:

<<[-]word
    here-document
delimiter

So it is the current source that is read from, which I think is stdin. Could someone decompose this into smaller chunks, that I can understand?

I think delimiter corresponds to EOF in my example, right?

And here-document is probably the text I type in in stdin, right?

I fail to see what is word.