<sup> makes words go like thiiiiis.
<sub> makes them do thiiiiis.
<small> makes words go little. The more <small> you have the smaller the word.
Same thing applies with <big>.
<u> makes underlines.
Go here for Ｆｕｌｌ Ｗｉｄｔｈ.
̛̰̖̲̰͑ͨ͒̌͑̍̿̈͘Z̨̜̲̥̯̮̭͍̳ͧͣ͋̊̋͗Ȁ̪̼̠͎͒ͨ́̚͘͢͞L̸͉̬̻͌̒͑̊̽͡Ğ̝̮̝̗̲ͧ͝Ȍ͍̪̪̖͕̟͈̝̰̆͋̾̀ is found here.
Go here if you want some uʍop əpısdn.
Of course these are just basic things. You can also look at the HTML button for the codes if youre not up for searching through Google for them.
The button is here:
you betray the secrets of the trade
for those who never learned
<code> makes your text monospaced, <pre> puts your text in a grey box
This tool provides you with characters that match what you draw.
This tool lets you draw in monospace ASCII which you can then put in <code> on Tumblr.
This tool makes big-ass letters with text. Everything but the AOL fonts require monospace (<code>).