'Cool fonts' and 'different fonts' searches are looking for variety — as many distinct copy-paste styles as possible in one place. That's the fancy text generator and the Unicode text converter, which show them all at once.
This guide is the visual index: what each style looks like, and which ones are safe to use where.
Bold, sharp, and technical
Bold (𝗰𝗼𝗼𝗹) and bold italic for weight; monospace (𝚌𝚘𝚘𝚕) for a code-terminal look; fraktur (𝔠𝔬𝔬𝔩) for gothic blackletter. Bold is the most widely supported style of all.
Flowing and decorative
Plain and bold script (𝒸ℴℴ𝓁) for handwriting; double-struck (𝕔𝕠𝕠𝕝) for an outlined maths look; small caps (ᴄᴏᴏʟ) for a quiet, even style.
Enclosed and framed
Bubble (ⓒⓞⓞⓛ) and squared (🄲🄾🄾🄻) wrap each letter; brackets, hearts, and sparkles frame the whole phrase. Frames are the safest because the letters inside stay plain.
Layout and effect
Letter-spaced and full-width (ｃｏｏｌ) add air; upside-down and reversed flip the line; glitch adds a distorted overlay. Use these sparingly — they change layout more than letterform. For which styles render everywhere, see copy and paste fonts.