Type lowercase text and it's converted into small-capital Unicode letters (ᴀʙᴄ...) — a subtler alternative to shouting in full uppercase, commonly used for stylized usernames and headers. Note that 'q' and 'x' have no dedicated small-capital Unicode code point, so they fall back to plain lowercase.
Small caps is a typographic technique that renders lowercase letters as smaller-sized capital letters, historically used in print to give headings or initials a subtle, refined emphasis. Online, it's popular for stylized usernames and post headers when you want something to stand out without the "shouting" feel of full uppercase (HELLO).
Unlike a CSS font-variant style, the characters this tool produces are genuine standalone Unicode letters drawn from blocks like IPA Extensions and Phonetic Extensions. Because they're real characters rather than a rendering trick, they copy as plain text anywhere and keep their small-caps appearance regardless of the font used at the destination.
Unicode simply has no dedicated small-capital code point defined for lowercase q or x, so those two letters are left unchanged in the output — this is a limitation of the standard, not a bug. This tool also only handles Latin letters (a-z); digits, Hangul, Chinese, and other non-Latin text pass through unconverted.