Letter spacing, also known as tracking, is the distance between adjacent characters in a line of text. Kerning adjusts the spacing between specific character pairs such as "AV" or "To," whereas tracking uniformly increases or decreases the spacing across an entire block of text. In CSS, tracking is controlled with the letter-spacing property.

In Japanese typesetting, the default letter spacing is zero, a style called "beta-gumi" (solid setting). Kanji and hiragana are designed to fit within a square body, so placing characters side by side with no gap produces even spacing automatically. English text, by contrast, consists of characters with varying widths, so the font's built-in metrics (character width data) automatically adjust the spacing.

In headings and logos, increasing letter spacing (positive tracking) creates a sense of elegance and openness, while decreasing it (negative tracking) conveys density and tension. For Japanese headings, a letter spacing of 0.1em to 0.2em is common, providing a slightly wider spacing than body text that balances readability with visual appeal.

Letter spacing does not affect the character count itself, but it has a significant impact on the physical space that a given number of characters occupies. The number of characters that fit on a business card, in a poster headline, or inside a button label all depend on the letter-spacing setting. Increasing letter spacing by just 0.1em makes a 10-character string roughly one character longer in display width.

From an accessibility standpoint, WCAG 2.1 Success Criterion 1.4.12 (Text Spacing) requires that content remain usable when users increase letter spacing to at least 0.12em. If text is packed into a fixed-width container, widening the letter spacing can cause text to overflow or overlap.

The CSS letter-spacing property is inherited. Letter spacing set on a parent element is applied to all child elements as well, so wide spacing on a heading will also affect any link text inside it. To prevent unintended inheritance, child elements must explicitly set letter-spacing: normal. CSS typography guides on Amazon cover these nuances in detail.