Tumblr's micro-blogging platform is based on a variety of short and simple blog posts created with equally simple tools, including a rich text editor that makes post customization a breeze. The editor helps you add special formatting to your text-based blog updates, including bolding, italicizing, cross-outs -- also called strikethrough text -- and underlining. For more advanced users, an HTML editor is available to facilitate manual formatting.

Formatting with the Rich Text Editor

The rich text editor appears by default when you create a new "Text" post on Tumblr. Begin by typing your desired comments in the "Post" box, then highlight the text to which you want to apply special formatting. Using the toolbar directly above the entry field, click the "Bold" icon -- which looks like a capital "B" -- to apply a bold stroke to the text. Click the "Strikethrough" icon -- which looks like a capital "S" with a horizontal line through it -- to strike through (or cross out) the text you've entered.

Strikethrough and Bolding with HTML Coding

In formatting your actual text content, there's little difference between HTML and rich text editors. When it comes to more complex elements -- like tables of data, fillable forms or JavaScript programs -- HTML is far superior. If you're already coding a few lines elsewhere on the page, stick with the HTML editor when adding special formatting to the main text content on your Tumblr blog. For example, add the "<b>" and "</b>" tags around the words or phrases you want bolded. To strikethrough or cross out text, use the "<s>" and "</s>" tags instead.