The character symbols for copyright and registered trademark are part of the HTML specification (those are the C and R in the circle symbols) but the superscript TM symbol to denote trademark is not. This short post looks at how you can insert the TM symbol into your HTML but be aware that because it is not supported by the HTML spec it may not render across all browsers and all operating systems correctly.
The following is an image depicting the TM symbol as it is normally used, subscripted at the end of the trademark word:
You can render the TM symbol in HTML with the following entities:
Please note as mentioned in the first paragaph that these are not supported by the HTML specification. They should render correctly across browsers and operating systems but there is no guarantee.
And just for the sake of reference, these are the entities for the copyright © symbol:
and for the registered trademark ® symbol: