Read more... Link

I've seen some people use some sort of HTML tag or other setting to make their posts that are longer than a few paragraphs be hidden under a "Read More..." link when using Dw in the Reading page. I looked it up and I tried but I guess it only shows up for other people on their Reading pages so I thought I'd ask. How do you it? I honestly think that should be the default as some people seem to write longer pieces, which is great.