At the very top of an article is the lead section; the name of the article is always bolded. Bolding is done by putting three apostrophes on each side of the text. Except for the article name, it is rarely used in articles.
A "level 2" heading is one with a pair of equal signs on each side. It's the highest level used in articles. If you enter a Level 1 heading, it "will " work, you'd be wrong to do so.
Level 2 and level 3 headings are very common in articles. Level 4 is less common.
Next, let's italicize some text by putting two apostrophes on each side.