stylistic:tone, quality:corruption, stylistic:style_transfer, linguistic:voice_change
Principles of the typographic craft

Three fundamental aspects of typography are legibility, readability, and aesthetics. Although in a non-technical sense "legible" and "readable" are often used synonymously, typographically they are separate but related concepts. Legibility and readability tend to support aesthetic aspects of a product.

Legibility describes how easily individual characters can be distinguished from one another. It is described by Walter Tracy as "the quality of being decipherable and recognisable". For instance, if a b and an h, or a 3 and an 8, are difficult to distinguish at small sizes, this is a problem of legibility. Typographers are concerned with legibility insofar as it is their job to select the correct font to use. Brush script is an example of a font containing many characters that might be difficult to distinguish. The selection of cases influences the legibility of typography because using only uppercase letters (all-caps) reduces legibility.

Readability refers to how easy it is to read the text as a whole, as opposed to the individual character recognition described by legibility. Use of margins, word and line spacing, and clear document structure all impact readability. Some fonts or font styles, for instance sans-serif fonts, are considered to have low readability and so are unsuited for large quantities of prose.

Legibility "refers to perception" (being able to see as determined by physical limitations of the eye), and readability "refers to comprehension" (understanding the meaning). Good typographers and graphic designers aim to achieve excellence in both.

"The typeface chosen should be legible. That is, it should be read without effort. Sometimes legibility is simply a matter of type size; more often, however, it is a matter of typeface design. Case selection always influences legibility. In general, typefaces that are true to the basic letterforms are more legible than typefaces that have been condensed, expanded, embellished, or abstracted.

However, even a legible typeface can become unreadable through poor setting and placement, just as a less legible typeface can be made more readable through good design.

Studies of both legibility and readability have examined a wide range of factors including type size and type design, comparing serif vs. sans-serif type, roman type vs. oblique type and italic type, line length, line spacing, color contrast, the design of right-hand edge (for example, justification, straight right hand edge) vs. ragged right, and whether text is hyphenated. Justified copy must be adjusted tightly during typesetting to prevent loss of readability, something beyond the capabilities of typical personal computers.

Legibility research has been published since the late nineteenth century. Although there often are commonalities and agreement on many topics, others often create poignant areas of conflict and variation of opinion. For example, Alex Poole asserts that no one has conclusively answered which typeface style, serif or sans serif, is more legibile, although strong opinions exist. Other topics, such as justified vs. unjustified type, use of hyphens, and proper typefaces for people with reading difficulties such as dyslexia, continue to be debated.

Legibility is usually measured through the speed of reading, with comprehension scores used to check for effectiveness (that is, not a rushed or careless read). For example, Miles Tinker, who published numerous studies from the 1930s to the 1960s, used a speed of reading test that required participants to spot incongruous words as an effectiveness filter.

The Readability of Print Unit at the Royal College of Art under Professor Herbert Spencer with Brian Coe and Linda Reynolds did important work in this area. It was one of the centers that revealed the importance of the saccadic rhythm of eye movement for readability—in particular, the ability to take in (i.e., recognise the meaning of groups of) about three words at once and the physiognomy of the eye, which means the eye tires if the line required more than three or four of these saccadic jumps. More than this is found to introduce strain and errors in reading (e.g., doubling). The use of all-caps renders words indistinguishable as groups, all letters presenting a uniform line to the eye, requiring special effort for separation and understanding.

Currently, legibility research tends to be limited to critical issues or the testing of specific design solutions (for example, when new typefaces are developed). Examples of critical issues include typefaces for people with visual impairment, typefaces and case selection for highway and street signs, or for other conditions where legibility may make a key difference.

Much of the legibility research literature is atheoretical—various factors were tested individually or in combination (inevitably so, as the different factors are interdependent), but many tests lacked a model of reading or visual perception. Some typographers believe that the overall word shape (Bouma) is essential in readability and that the theory of parallel letter recognition is wrong, less important, or not the entire picture. Word shape differs by outline, influenced by ascending and descending elements of lowercase letters and enables reading the entire word without having to parse out each letter.

Readability also may be compromised by letter-spacing, word spacing, or leading that is too tight or too loose. It may be improved when generous vertical space separates text lines, making it easier for the eye to distinguish one line from the next, or previous line. Poorly designed typefaces and those that are too tightly or loosely fitted also may be less legible. Underlining also may reduce readability by eliminating the recognition effect contributed by the descending elements of letters.

Periodical publications, especially newspapers and magazines, use typographical elements to achieve an attractive, distinctive appearance, to aid readers in navigating the publication, and in some cases for dramatic effect. By formulating a style guide, a publication or periodical standardizes with a relatively small collection of typefaces, each used for specific elements within the publication, and makes consistent use of typefaces, case, type sizes, italic, boldface, colors, and other typographic features such as combining large and small capital letters together. Some publications, such as The Guardian and The Economist, go so far as to commission a type designer to create customized typefaces for their exclusive use.

Different periodicals design their publications, including their typography, to achieve a particular tone or style. For example, USA Today uses a bold, colorful, and comparatively modern style through their use of a variety of typefaces and colors; type sizes vary widely, and the newspaper's name is placed on a colored background. In contrast, The New York Times uses a more traditional approach, with fewer colors, less typeface variation, and more columns.

Especially on the front page of newspapers and on magazine covers, headlines often are set in larger display typefaces to attract attention, and are placed near the masthead.

Typography utilized to characterize text: Typography is intended to reveal the character of the text. Through the use of typography, a body of text can instantaneously reveal the mood the author intends to convey to its readers. The message that a body of text conveys has a direct relationship with the typeface that is chosen. Therefore, when a person focuses on typography and setting type, they must pay very close attention to the typeface they choose. Choosing the correct typeface for a body of text can only be done after thoroughly reading the text, understanding its context, and understanding what the text is wishing to convey. Once the typographer has an understanding of the text, then they have the responsibility of using the appropriate typeface to honor the writing done by the author of the text. Knowledge required to choose the correct typeface comes with understanding the historical background of typefaces and understanding the reason that typeface was created. For example, if the text is titled "Commercial Real Estate Transactions" and elaborates on the real estate market throughout the body, then the appropriate typeface is a serif typeface, because the author intends to inform his audience on a serious topic and not entertain his audience with an anecdote; a serif typeface would convey a sense of seriousness to the audience instantaneously. The typographer would also employ larger type for the title to convey its importance, which directly informs the reader of the structure in which the text is intended to be read, and increases readability from varying distances.

Typography utilized to make reading practical: Typography not only must honor the tone of the text but also share the responsibility of making the audience commence reading and sustaining the audience's attention throughout the text. Although typography can potentially attract the reader's attention and create a beautiful/attractive piece of text, the craft of typography is not limited to the aesthetic appeal of the text. On the contrary, the object of typography is to make the reading experience practical and useful. Bold colors, multiple typefaces, and colorful backgrounds in a typographic design may be eye-catching; however, it may not be appropriate for all bodies of text and could potentially make text illegible. Overuse of design elements such as colors and typefaces can be unsettling, preventing the text from conveying its message to readers. A study from 2020 found that the participating subjects felt music sounded "more pleasant" when the CD cover featured round typeface.