"Sans Serif" is a term to indicate a typeface lacking in serifs which are the short lines stemming from the strokes of a letter. Other names for this type class are "unserifed" and "Grotesque"/"Grotesk" to describe their unattractive look compared to the Serif faces which dominated at their "introduction" in 1816.
Common Examples: Helvetica, Geneva, Futura, Arial, Bauhaus, Univers.
Although the modern versions of sans serif came about in 1816, unserifed letters have appeared since ancient Greece and were used by the Etruscans and Romans. While the sharp Roman alphabet with its strong serifs is the basis of our modern alphabet and lettering, this was an invention of Imperial Rome as under the Roman Republic, sans serif lettering was the standard.
Sans serifs existed well into the Renaissance but disappeared in the 1470s when metal type was introduced, probably due to the bias of the type creators, especially Manutius, and its seemingly lower class status where it was used in Renaissance Italy by populist movements.
It wasn't until William Caslon, a famous English engraver and typographer, created a new (uppercase only) alphabet for signs that Sans Serif type was used again. In Leipzig, about ten years later, the first of the Grotesks, with full upper and lowercase letters was created. Helvetica and Franklin Gothic are representative of these early types. The primary impetus for the redevelopment of the sans serif was the Realist art movement which, in typography, held the more simple script of the less educated classes as worthy of inclusion. After their initial introduction, sans serifs developed slowly and remained stagnant for almost 100 years until the 1920s.
During the twentieth century, sans serif fonts evolved dramatically due to three influences:
- Findings of earlier sans serif faces (such as ancient Greek ones) which were generally lighter and more "flowing" as they were drawn freehand. While the letters tended to be composed of entirely straight lines, the curves had a very large aperature. Lithos is a popular example.
- Applying the Bauhaus theory of design to sans serifs, resulting in less ornate yet more geometrically precise typefaces. Avant Garde is one of the most common examples.
- Designing sans serif faces on humanistic forms. Frutiger and Myriad are two of this category.
Since modern sans serifs have only existed for less than 200 years (and have only been accepted for less than 100), the classification system is much simpler than that of their serifed brothers. Generally there are three categories:
- Early/Neo-Grotesque - Based on the initial sans serifs, these typefaces typically have strokes with little modulation and small openings/aperatures (for example on the C and S). The character shape is, overall, a standard serif typeface with all serifs removed. Helvetica, Arial, Univers, and Franklin Gothic are representative of this category
- Geometric - Stemming from the Bauhaus theory of design, these typefaces are characterized by generally having no modulation whatsoever and completely minimalistic: curves and dots, when required, are perfectly round (the O is a circle, for example), lines are straight, descenders on the j and y lack a curve, etc. Futura, Bauhaus, Avant Gardes, and Century Gothic are fairly canonical examples.
- Humanist - Generated by a more "freehand" approach, these typefaces are derived from actual writing (while not venturing into the Script category). Marked by more ornamentation and less precise shaping than Geometrics and somewhat more curved than a 'typical' Serif like Times. Myriad, Lithos, Optima, and Shannon all fall in this category.
Generally sans serifs should not be used for blocks of text. They are designed for legibility, not readability. As always, there are exceptions but this generally holds. There is a significant distinction between these two concepts - sans serif letters are more easily recognized individually but, as the amount of text becomes larger, the lack of information on the letters means the reader spends more time deciphering words, especially when grouped together in multiple sentences. Therefore, while it helps you read "STOP" more quickly, it makes reading Shakespeare that much harder.
Since sans serifs are primarily designed for very short blocks of text, they usually lack the additional characters and faces that flesh out a large type family. The most notable lack is that usually (by design), sans serifs do not have an italic. In their place is an oblique which is simply an angular shift of the characters, much as pressing the "italic" button in a word processor.
Therefore, if using a sans serif, it should be used for short blocks of text such as titles (where it provides good contrast with the regular text face) or signs (which consist of short bursts of text to be read quickly).
Personally, I don't generally like sans serif faces and would rather contrast with a different serif face that uses either weight and/or style for contrast.
Fonts You May Have Missed:
Often, typefaces are created for a specific purpose. This is also the case with sans serifs:
Gill Sans - Gill Sans was designed in 1916 by Eric Gill for the London Underground's signs. Mind the gap, please! Gritchka informed me that the correct face is either Johnston's Railway Type or Johnston Underground by Edward Johnston. Eric Gill's Gill Sans is a similar looking face and he also worked for the LU, leading to the confusion. Now if anyone knows what face Blur usually uses for their logo, let me know.
- DIN Schriften - This type family was commissioned by Germany and is the Deutsche Industrie-Norm. The primary benefit of this family is that it is easily reproducible and was used for road signs and license plates in West Germany (it may still be in use). While it is easy to reproduce, in actuality, its geometric design tends to work somewhat against it in practical situations (such as reflective letters on a road sign at night where the reflection causes the circles to wash out, for instance).
- VAG Rounded - Official face of the Volkswagen Auto Group, it was created in 1979.
- Frutiger - Designed by Adrian Frutiger in 1968, this typeface was commissioned by the Charles De Gaulle Airport in Paris for its signs.
- Bell Centennial / Bell Gothic - Bell Gothic was developed in 1937 to be used by AT&T for telephone books. It was replaced in 1978 (AT&T's 100th anniversary) by Bell Centennial. Both were designed with the same goals: As legible as possible in small sizes, densely formatted as lists, with good distinction between capital letters and numbers.
- OCR-A - Somewhat difficult for humans to read, this face, released in 1968 was the first to meet the U.S. Bureau of Standards criteria. It also meets ANSI and German DIN standards for OCR. Update: SharQ has pointed out that there are a few serifs in OCR-A (the lowercase i & j and the uppercase T & D, primarily). OCR-B (by Adrian Frutiger in 1968) is almost entirely devoid of serifs (there is one on the lowercase i and j) and is easier for humans to read but pushed the limits of what OCR machines could in the early '70s.
- Spartan Classified - American Type Founders released this in 1936 for classified ads in newspapers.
- Letter Gothic - Created by Roger Robertson around 1960 for the IBM Selectric typewriter.
- Orator - John Scheppel created this, another typeface for IBM typewriters.
- Briem Akademi - Originally was a homework assignment at the Royal Academy of Fine Arts in Copenhagen.
- Neuland - Based on the handwriting of Rudolf Koch in 1923, this was used for the titles of "Jurassic Park"
Thanks to Elements of Typographic Style by Robert Bringhurst and http://www.adobe.com/type