This paragraph follows an h3 heading. It will be the first time I will get to see something that looks like a REAL web page, although I'll have seen something similar in a wordprocessor document.
The second paragraph will be just as boring as the first, but it will demonstrate the fact that a line break is added between the two paragraph blocks by the browser. What will follow will be another heading.
The final paragraph demonstrates that a line break is automatically inserted after a heading as well. It means that the document looks well presented. Notice the font that this is being shown in. It is the DEFAULT font, chosen by your browser (usually Times New Roman).