The Stack Exchange engine allows only the following safe, whitelisted subset of HTML tags:
<a> - hyperlink.
<b> - bold, use as last resort <h1>-<h3>, <em>, and <strong> are
<blockquote> - specifies a section that is quoted from another source.
<code> - defines a piece of computer code.
<del> - delete, used to indicate modifications.
<dd> - describes the item in a <dl> description list.
<dl> - description list.
<dt> - title of an item in a <dl> description list.
<em> - emphasized.
<h1>, <h2>, <h3> - headings.
<i> - italic.
<img> - specifies an image tag.
<kbd> - represents user input (usually keyboard input).
<li> - list item in an ordered list <ol> or an unordered list <ul>.
<ol> - ordered list.
<p> - paragraph.
<pre> - pre-element displayed in a fixed width font and and
unchanged line breaks.
<s> - strikethrough.
<sup> - superscript text appears 1/2 character above the baseline
used for footnotes and other formatting.
<sub> - subscript appears 1/2 character below the baseline.
<strong> - defines important text.
<strike> - strikethrough is deprecated, use <del> instead.
<ul> - unordered list.
<br> - line break.
<hr> - defines a thematic change in the content, usually via a
Note that since we allow the above HTML tags, to have tags show up as text you need to escape the < character. You can escape '<' by marking it as code (with indentation or backticks as is done below) or by using the HTML entity <
The following attributes are allowed on the <img> tag, but note that the mobile theme enforces a maximum width of 90%, so specifying a height might not scale the image proportionally on the mobile sites.
The attribute order is important! Using a different order (e.g., height before width) will strip the tag!
width="" (up to 999; do not include the 'px' extension)
height="" (up to 999; do not include the 'px' extension; see note above)
The following attributes are allowed on the <a> tag:
HTML tags unlisted above are stripped from the output. They may render in the client preview, but they will always be removed on the server.
You must enter the tags exactly as shown. Any deviation from this list—adding extra spaces, using single quote or no quotes, etc.—means the tag will be stripped.
We do not (and will not) allow <table> tags. Sorry. This is intentional and by design. If you need a quick and dirty "table", use <pre> and ASCII layout.