Using HTML entities is the right way to ensure all the characters on your page are validated. However, often finding the right entity code requires scanning through 250 rows of characters.
This lookup allows you to quickly find the entity based on how it looks, e.g. like an < or the letter c.
To reset the keywords, clear your cookies for this page and the default keyword dictionary.
The lookup searches the html entities for matches to the searched character based on how your character looks. For instance, the letter c would match © and ¢ entity, because of the way they look.
There's no clever logic behind this, only the most powerful computer known to man - man's own brain.
Each entity has had a list of 'like' matches added to them by hand and eye. This is stored in a local dictionary file and loaded in during start-up (since it's so small there's no point in using an AJAX like solution).
The entity lookup also supports word searches and multiple searches space separated, such as copy and cent.