Corrects markup in a way compliant with the latest standards, and optimal for the popular browsers. it has a comprehensive knowledge of the attributes defined in the html 4.0 recommendation from w3c, and understands the us ascii, iso latin-1, utf-8 and the iso 2022 family of 7-bit encodings. in the output:

* html entity names for characters are used when appropriate.
* missing attribute quotes are added, and mismatched quotes found.
* tags lacking a terminating '>' are spotted.
* proprietary elements are recognized and reported as such.
* the page is reformatted, from a choice of indentation styles.
tidy is a product of the world wide web consortium.