Glossary

Term	Definition
absolute unit	In CSS, length units that are dependent on the output medium. Absolute units include in (inch), cm (centimeter), mm (millimeter), pt (point), and pc (pica). Contrast with relative unit.
alignment	The horizontal or vertical positioning of an element. Typical horizontal alignments include left, right, and center; typical vertical alignments include baseline, sub, super, top, text-top, middle, bottom, and text-bottom.
ascender	The upward-pointing stem of a letter, such as "d" or "h", that extends toward the cap line.
baseline	The line on which the lowest terminals of most commonly used letters, such as "n" or "e", rest, excepting those with descenders, such as "g" or "p". The line as a whole is said to rest on the baseline.
blowout	An event where a layout renders in an unexpected and generally undesirable way. Blowouts typically inform future test cases of the layout.
bold	Of a font or typeface, having thicker strokes than its normal form. The last word in this sentence is bold.
brute force	An unskilled, inelegant coding style in which the developer relies on a computer’s processing power to achieve a result instead of crafting orderly, efficient code.
cap line	The line met by the top terminals of most uppercase letters, such as "H" or "R", and sometimes exceeded by the ascenders of some lowercase letters, such as "b" or "k".
centered	A form of typographical justification that positions an element horizontally equidistant from the left and right edges of its container element.
character	A letter, number, or symbol, such as "Y", "4", or "%".
character encoding	A precisely-defined correspondence between characters and the numbers used to represent them in electronic systems, intended to achieve consistent storage, transmission, or display of data. Common character encoding schemes include ASCII, Unicode, and UTF-8.
character set	The full range of characters in a font used for electronic documents, in which each character assumes a unique code position within the font.
code position	The decimal or hexadecimal location of a character's bit encoding (number) within its character set.
container element	A parent element that comprises one or more child elements. A container element typically determines the content flow and/or positioning context of its child elements.
copy	A broad term for content delivered by a document's author. May include text, images, tables, links, lists, etc.
descender	The downward-pointing stem of a letter, such as "p" or "y", that extends below the baseline.
edge case	In a layout, a design requirement or issue that is confined to a proportionally small number of elements or documents.
em	A unit of typographical measurement equal to the currently specified point size. Originally derived from the width of the uppercase "M" in the given typeface, this unit ensures consistency across all fonts at a given point size. Thus, 1 em in a 16-point font is 16 points.
en	A unit of typographical measurement equal to one-half the currently specified point size. Originally derived from the width of the lowercase "n" in the given typeface, this unit ensures consistency across all fonts at a given point size. Thus, 1 en in a 16-point font is 8 points.
flush	In a layout, a state in which no whitespace is present between two content elements, or between a content element and the edge of its container element.
flush left	A form of typographical justification that positions an element horizontally at the left edge of its container element. As applied to text, also called ragged right.
flush right	A form of typographical justification that positions an element horizontally at the right edge of its container element. As applied to text, also called ragged left.
font	The collection of characters in a given style and/or weight, e.g., normal, bold, or italic, for a particular typeface.
functional notation	To provide property values in CSS in a format that resembles a function call, e.g., `body {background-image:url("mybg.gif");}`.
generic font family	In CSS, a broad class of similar fonts used in a prioritized list of fonts. Common generic font families include serif (such as Times New Roman, Bodoni, and Garamond), sans-serif (such as MS Arial, MS Verdana, and Univers), and monospace (such as Courier, MS Courier New, and Prestige).
CSS Keyword	A CSS keyword is a literal string that has a special meaning when used as a value for a css property. Examples: `inherit`, `smaller`, `white`.
glyph	A single letter, number, symbol, or ligature within a given font. Usually, but not always, a synonym for character.
grid	A composition device used to ensure that all elements in a layout will appear at coordinates that can be easily predicted. Effective grid use can make a layout more coherent and improve readability and comprehension of the content.
gutter	The whitespace present between two adjacent margins, apparent as a result of justification, bordering, or rule placement.
hanging punctuation	A typographical method of placing punctuation marks, such as quotation marks and bullets, so that they do not disrupt the flow of a body of text or break the margin of alignment. So named because the punctuation appears to "hang" in the margin, and is not incorporated into the block or column of text. Also called exdentation.
hyphenation	The practice of separating words at syllable boundaries with a hyphen character (-) in order to make them fit better on a line and avoid unnecessary trailing whitespace. Modern editing software has refined the text justification process, making hyphenation largely superfluous. Also called syllabication.
italic	Of a font or typeface, a style somewhat emulating cursive writing that slants characters slightly. The last word in this sentence is italic.
justification	The typographical practice of aligning multiple lines of text precisely to one or both of their common margins. Typically referred to in its individual forms as left, right, center, or full justification.
justified	A form of typographical justification that positions text to align precisely with both its left and right margins, usually accomplished by incrementally increasing or decreasing word spacing (and sometimes letter spacing) by minute amounts. Also called fully-justified.
kerning	The typographical process of adjusting the spacing between individual characters in a line of text rendered in a proportional font to achieve a visually pleasing result.
KISS	Acronym for "Keep It Simple, Stupid", "Keep It Short and Simple", etc. Based on the principle that reducing complexity in a system (typically a factor of the number of system elements) reduces the potential for errors, and thus that the avoidance of unnecessary complexity should be a key goal in any design effort.
leading	In typography, the (typically vertical) distance between adjacent lines of type. So called because during the era of offset printing, this space was controlled by inserting strips of lead between lines of type to separate them.
letter spacing	In typography, the amount of space between a group of letters, adjusted to affect density in a line or block of text. Also called tracking, and often confused with kerning.
ligature	A typographic method by which two or more glyphs are combined into one, with the resulting single glyph replacing the original two consecutive characters. Common Latin alphabet ligatures include & (combining "E" and "t"), Æ (combining "A" and "E"), and ß (combining "s" and "s" or "s" and "z").
lining figures	Characters, typically numerals, of a consistent height that all share the same baseline and cap line, resulting in a consistently sized line. Contrast with non-lining figures, which are numerals typeset with varying heights, some extending above the cap line or below the baseline.
lorem ipsum	In publishing, placeholder or filler text commonly used to demonstrate the structure and visual layout of a document by removing the distraction of meaningful content. The lorem ipsum text is typically derived from a section of a Latin text by Cicero with words altered, added and removed that make it nonsensical in meaning (and thus not proper Latin). For example, "Lorem ipsum dolor sit amet, consectetur adipisici elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua."
mean line	Of a font, a point exactly half the distance from the baseline to the cap line. This is often, but not necessarily, the height of the lowercase letters (the x-height). Also called midline.
monospaced font	A font whose characters each occupy the same amount of horizontal space, such that typically-narrow letters like "i" and typically-wide letters like "w" are the same width. Also called fixed-pitch or fixed-width font. `This sentence is in a monospaced font.` Contrast with proportional font.
non-lining figures	Characters, typically numerals, typeset with varying heights, some extending above the cap line or below the baseline. Contrast with lining figures, which are numerals of a consistent height that all share the same baseline and cap line, resulting in a consistently sized line. Also called old-style figures.
oblique	A form of type that slants slightly to the right, used in the same manner as italic type. Unlike italic, however, it does not use different glyph shapes; it uses the same glyphs, but distorted by slanting. Often confused with italic.
pagination	The process, manual or automatic, of dividing content into separate pages, either electronic or printed. The latter is often simply an instance of the former, rendered to print.
pica	A typographical unit of measure corresponding to 1/72 of a foot, and therefore equal to 1/6 of an inch. The pica contains 12 point units of measure.
point	The smallest unit of typographical measure (a subdivision of the pica). The current desktop publishing point is defined as 72 points to the inch (1 point = 1/72 inch). There are thus 12 points in a pica.
proportional font	A font whose characters occupy different amounts of horizontal space, such that typically-narrow letters like "i" and typically-wide letters like "w" are not the same width. Also called variable-pitch font. This entire definition is in a proportional font. Contrast with monospaced font.
ragged	The typographical practice of allowing multiple lines of text to align as they fall against one of their common margins, making no attempt to align them to the other. Typically referred to in its individual forms as ragged right or ragged left.
recommendation	The World Wide Web Consortium's (W3C) official title for what is often referred to as a "Web standard." Typically capitalized as Recommendation. Because the W3C does not certify anyone, because it has no bylaws or procedures to penalize members for violating Recommendations in their implementations, and because the practices set forth in W3C literature do not carry the force of law, the W3C only applies the term "standard" to other organizations' work, as appropriate.
relative unit	In CSS, length units that are relative to another element's length. Relative units include em (ems, the height of the element's font), ex (x-height, the height of the letter "x"), and px (pixels, relative to the canvas resolution). Contrast with absolute unit.
rendering engine	The software portion of a Web browser that turns HTML and CSS into viewable pages, thus rendering a Web page from its native code. Also called a layout engine.
river	A typographical idiosyncrasy in which (typically vertical) visible gaps of whitespace appear to run through a paragraph of text due to a coincidental alignment of spaces. Rivers are most noticeable with wide inter-word spaces in monospaced fonts, but are less noticeable with proportional fonts.
rule	The generic name for any line of arbitrary length and weight in a layout, as in "horizontal rule." In CSS, a style definition that consists of a selector and one or more declarations.
sans-serif font	A typeface that does not have the small projecting features (serifs) at the ends of character strokes, such as Arial. Modern convention holds that sans-serif fonts are preferred over serif fonts for online text, while serif fonts are preferred for print. Contrast with serif font.
serif font	A typeface that has the small projecting features (serifs) at the ends of character strokes, such as Times Roman. Modern convention holds that serif fonts are preferred over sans-serif fonts for print, while sans-serif fonts are preferred for online text. Contrast with sans-serif font.
small caps	A typographical feature in which smaller uppercase letters are set at the same height and weight as the font's lowercase letters and used as though they were lowercase, creating a visually distinctive appearance from both equivalent uppercase characters and surrounding text.
stem	The (typically vertical) ascender or descender of a character that extends above the x-height or below the baseline, respectively. The letters "d" and "q" have stems; the letters "o" and "e" do not.
subscript	A number, figure, symbol, or other character that appears smaller than the normal line of type and is set slightly below it, typically extending below the baseline. Subscripts are often used in formulas, mathematical expressions, footnotes, and other references. This sentence ends with a subscript₁. Contrast with superscript.
superscript	A number, figure, symbol, or other character that appears smaller than the normal line of type and is set slightly above it, typically extending above the cap line. Superscripts are often used in formulas, mathematical expressions, footnotes, and other references. This sentence ends with a superscript¹. Contrast with subscript.
symbol font	Any one of a number of typefaces containing primarily symbolic glyphs, such as playing card suits, Greek letters, emoticons, arrows, lines, etc. Common symbol fonts include Symbol, Bookshelf Symbol 7, and the Wingdings series.
taxonomy	The deliberate hierarchical arrangement of a body of related objects. For example, the biological taxonomy "domain > kingdom > phylum > class > order > family > genus > species", or the CSS taxonomy "rule > selector > declaration > property > value".
test case	A scenario of site use or misuse, worked out in advance by its development team and deliberately applied in order to ensure that the site will behave as expected under most reasonable and foreseeable circumstances.
typeface	A collection of fonts that shares strict commonality of design across all of its fonts. A stroke is part of a glyph, which is either identical to or part of at least one character. A complete collection of characters of identical weight and/or style is a font.
weight	In typography, the relative heaviness or lightness of rules, borders, and character strokes. In CSS, the importance or lack thereof of a directive, such as a style rule.
whitespace	The portion of a layout left unoccupied; that is, all space between graphics, margins, gutters, columns, lines of type, words, figures, or other objects drawn or rendered in an online or printed page.
widow	A word or short line at the end of a paragraph that is left dangling at the top of a column or page, separated from the rest of the paragraph by the previous break. The Chicago Manual of Style offers this definition: A paragraph-ending line that falls at the beginning of the following page/column, thus separated from the rest of the text. Contrast with orphan.
x-height	The distance between the baseline and the mean line in a typeface. Typically, this is the height of the lowercase letter "x" in the font, hence its name and the CSS reference unit "ex".