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In typography, kerning is the process of adjusting the spacing between characters in a proportional font, usually to achieve a visually pleasing result. Kerning adjusts the space between individual letterforms while tracking (letter-spacing) adjusts spacing uniformly over a range of characters. In a well-kerned font, the two-dimensional blank spaces between each pair of characters all have a visually similar area. The term "keming" is sometimes used informally to refer to poor kerning (the letters r and n placed too close together being easily mistaken for the letter m). The related term kern denotes a part of a type letter that overhangs the edge of the type block. Metal typesetting The source of the word kern is from the French word carne, meaning "projecting angle, quill of a pen". The French term originated from the Latin cardo, cardinis, meaning "hinge". In the days when all type was cast metal, the parts of a typecasting sort that needed to overlap adjacent letters simply hung off the sort slug's edge. Those overhanging metal pieces were called kerns. At that time, the word kerning only referred to manufacturing the sorts with kerns, while adjusting space between letters during compositing was called inter-spacing or letter spacing. Because this method was not well-suited to some pairs of letters, ligatures were supplied for those glyph combinations, such as the French L’, or the combinations ff, fi, fl, ffi, ffl, and others. Digital typography In metal typesetting, kerning was labour-intensive and expensive because the matrices had to be physically modified. It was therefore only employed on letter combinations which needed it the most, such as VA or AV. With the arrival of digital fonts, it became much easier to kern many glyph combinations. Kerning values In digital typography, kerning is usually applied to letter pairs as a number by which the default character spacing should be increased or decreased: a positive value for an increase, a negative value for a decrease. The number is expressed in font units, one unit being a certain fraction of an em (one em is the type size currently used). Different fonts may use different units, but common values are 1000 and 2048 units/em. Thus, for 1000 units/em, a kerning value of 15 means an increase in character spacing by 0.015 of the current type size. (The kerning units for a given font are the same as the units used to express the character widths in that font.) Most kerning adjustments are negative, and negative adjustments are generally larger than positive ones. Adjustments for different pairs within a given font can range from a tiny 2 to over 100 (when expressed as 1000 units/em). The adjustments for a given pair vary greatly from one font to another. Negative kerning is widely used to fit capital letters such as T, V, W, and Y closer to some other capital letters on either side, especially A, and to some lower case letters on the right side, such as the combinations Ta, Te, and To. It is also used to fit a period (full stop) or a comma closer to these and to F and P, as well as to the lower case letters r, v, w, and y. Some other combinations that use negative kerning are FA, LT, and LY, and letters like A, L, and h followed by a quotation mark. Positive kerning is used mainly in conjunction with special characters and punctuation (for example, the lower case letter f followed by right parenthesis or quotation mark). Depending on the font, some small positive kerning may also be required for accented letters and for pairs like Bo, Dw, and TY. The table below contains a few exemplifying kerning pairs and their values. These values are based on 1000 units/em and the kerning pairs are ordered from the most negative to the most positive kerning value. The samples are taken from the kerning tables of the Minion Pro font. In other fonts the kerning may be very different. Which letters need to be kerned depends on which languages the font is to be used with. Since some combinations of letters are not used in normal words in any language, kerning these is not necessary. Non-proportional (monospaced) fonts do not use kerning, since their characters always have the same spacing. Kerning tables In older font formats, such as Microsoft's TrueType, the kerning values are specified in a simple kern table where each entry consists of a pair of characters and their kerning value. TrueType fonts typically have several hundred pairs, but some have more than a thousand. Since OpenType is a superset of TrueType kern tables are still supported for TrueType fonts packed as OpenType; however PostScript-based (CFF) OpenType fonts do not have this option. OpenType introduced a new, uniform way of specifying, among other things, kerning, via the Glyph Positioning Table (GPOS). The more recent font releases by Adobe no longer have kern tables at all, but only specify kerning via GPOS. Since an OpenType font may include thousands of glyphs, and consequently a huge number of pairs of characters that need kerning, OpenType fonts may have an elaborate system of tables and subtables, designed to minimize the overall storage space. (Kerning is treated as part of a broad range of new glyph positioning features which are stored in GPOS.) The system is based on the concept of glyph classes: instead of a one-dimensional table where each entry corresponds to a pair of characters, there are two-dimensional tables where each entry corresponds to a pair of classes of glyphs. A class includes several characters whose right-hand outline (and right side-bearing) is identical for kerning purposes, or several characters whose left-hand outline (and left side-bearing) is identical. All pairs of characters where the first one is from the first class and the second one is from the second class will require the same kerning value, so this value needs to be specified only once in the table. The rows in the two-dimensional table correspond to first-character classes, and the columns correspond to second-character classes. The kerning value for a given pair of characters is found in the table at the intersection of the classes to which they belong. This system is very economical, but is necessarily limited. For example, many of the classes may be quite small. Also, a font with many types of glyphs may require several such tables. Finally, many pairs remain that cannot be represented through classes. For them, simpler, one-dimensional tables are provided: each table is for a particular character that is the first in many pairs, and the entries contain the characters that are the second in these pairs, together with the corresponding kerning values. Here are a few examples of glyph classes in the Minion Pro font for the first character in a kerning pair: (d i l u), (h m n), (j q), (b o p), (v w y), (D O Q), (H I), (V W); and for the second character in a pair: (f i m n r), (h k l), (j p t u), (c d e o q), (v w y), (C G O Q), (B D E F H I K L N P R). A.... Discover the S D Kern popular books. Find the top 100 most popular S D Kern books.