Paste text to encode special characters as HTML entities — or paste entities to decode them back into readable text.
Encoding replaces characters like <, > and & with entities (<, >, &) so a browser shows them as text instead of reading them as markup. Named entities are easier to read; numeric entities work for every character, including symbols and accented letters with no common name.
Named or numeric — which should I use? Named where one exists (clearer in source), numeric for anything else. Browsers render both identically.
Why does pasted code break my web page? Unescaped < and & in text are parsed as the start of tags and entities. Encoding the five core characters — & < > " ' — prevents it.