Allowed HTML tags

They are:

address, a, abbr, acronym, b, big, blockquote, br, caption, cite, class, code, col, del, dd, div, dl, dt, em, font, h1…h6, hr, i, img, ins, kbd, li, p, pre, q, s, span, strike, strong, sub, sup, table, tbody, td, tfoot, tr, tt, ul, ol, var

And if you want to know what they do: w3schools.com