What Is Subscript vs Superscript?
Subscript text is positioned below the normal text baseline at a smaller size. In typography, it is called inferior text. In HTML, it is marked with the <sub> element. In Unicode, dedicated subscript digits span U+2080–U+2089 (₀ through ₉). Subscript is most common in chemistry (H₂O, CO₂, H₂SO₄) for atom counts in molecular formulas, and in mathematics for variable index notation (aₙ, xₖ).
Superscript text is positioned above the normal text baseline at a smaller size. In typography, it is called superior text. In HTML, it is marked with the <sup> element. In Unicode, superscript digits include ¹(U+00B9), ²(U+00B2), ³(U+00B3), and ⁰⁴⁵⁶⁷⁸⁹ (U+2070, U+2074–U+2079). Superscript is used for mathematical exponents (x², E=mc²), footnote markers (text¹), ordinal indicators (1ˢᵗ, 2ⁿᵈ), and trademark symbols (™).
The key distinction: subscript goes below the line; superscript goes above the line. Both modify positioning relative to the text baseline, but they serve completely different semantic purposes in scientific, mathematical, and typographic writing.