Slant your words elegantly with mathematical italic sans, italic serif, and cursive script letters.
Unicode has two true italics, a serif italic (𝐴𝐵𝐶) and a sans-serif italic (𝘈𝘉𝘊), plus bold versions of both. The sans-serif italic is the one to reach for on Instagram, X and Discord, because those platforms set everything in sans-serif and a serif italic reads as a font change rather than a slant. If you want something warmer than a slant, the two script alphabets (𝒜𝐵𝒞 and 𝓐𝓑𝓒) are the next step up, but they are much less legible at bio size. The italic alphabets have one gap: there is no italic h in the block, so the tool substitutes the Planck constant symbol ℎ, which is visually identical.
Italic carries meaning in ordinary writing (a title, a foreign word, a stressed syllable) and unicode italic lets you keep that meaning in a caption or a tweet that has no formatting. The habit worth keeping is the one from print: italicise a phrase, not a paragraph. A whole caption in italic loses the contrast that made it work and is harder to read on a phone. If you are writing for accessibility, remember that a screen reader will not say "italic". It will read the mathematical character names or skip them, so never put the only copy of a key word in a styled alphabet.
The italic h. Unicode never added a mathematical italic h because the Planck constant ℎ already existed in the Letterlike Symbols block, so every tool substitutes it. On most fonts it is indistinguishable; on a few it sits slightly differently.
No. None of the italic or script alphabets define digits, so numbers stay plain. If you need slanted numbers, bold italic is also letters-only, sans-serif bold is the nearest alphabet that includes digits.
Yes, wrap the words in underscores and WhatsApp renders them italic natively, and the text stays searchable. Use unicode italic on WhatsApp only for your About line, where the native formatting does not apply.