Serifs are referred to as such because of the small details that extend from the ending shapes of the characters; the origin of the word itself is obscure, various explanations have been given but none has been accepted as resolute.

Their origin can be traced back to the Latin alphabets of Roman times, probably because of the flares of the brush marks in corners, which were later chiseled in stone by the carvers.

They generally give better readability in print than on a screen, probably because of the better definition and evolution of the former in hundreds of years, while the latter technology is, on an evolutionary path, a newborn.

With the latest technologies and the high definition monitors that can rival the print definition, multiple scientific studies have been found inconclusive, showing that there is no discernible difference in readability between sans and serifs on the screen and as of today they are both used on the Web.

Within this general definition, there are multiples sub-families, as Old Style or Humanist.

The oldest ones, dating as far back as the mid 1400s are recognized for the diagonal guide on which the characters are built on; these are clearly visible for example on the e and o of Adobe Jenson.

They are neither antique nor modern and they date back to the 1700s and are generally numerous.

They tend to abandon some of the diagonal stress, but not all of them, especially keeping the o. Georgia and Baskerville are some well-known examples.

Modern Serifs tend to rely on the contrast between thick and thin strokes, abandon diagonal for vertical stress, and on more straight serifs. They appeared in the late 1700s.

Bodoni and Didot are certainly the most famous typefaces in this family.

Slab Serifs have little to no contrast between strokes, thick serifs, and sometimes appear with fixed widths, the underlying base resembles one of the sans more.

American Typewriter is the most famous typefaces in this family as shown in the following image:

It is the earliest of the bunch; its appearance is similar to the serif with contrasted strokes but without serifs and with angled terminals

Franklin Gothic is one of the most famous typefaces in this family.

It is plain looking with little to no contrast, small apertures, and horizontal terminals. They are one of the most common font styles ranging from Arial and Helvetica to Universe.

They have a friendly tone due to the calligraphic style with a mixture of different widths characters and, most of the times, contrasted strokes.

Gill Sans being the flag-carrier.

Based on the geometric and rigorous shapes, they are more modern and are used less for body copy. They have a general simplicity but readability of their characters is difficult.

Futura is certainly the most famous geometric font.

They are usually classified into two sub-families based upon the handwriting, with cursive aspect and connected letterforms. They are as follows:

Formal script

They are reminiscent of the handwritten letterforms common in the 17^th and 18^th centuries, sometimes they are also based on handwritings of famous people.

They are commonly used for elevated and highly elegant designs and are certainly unusable for long body copy.

Kunstler Script is a relatively recent formal script.

This is less precise and tends to resemble a more modern and fast handwriting. They are as recent as the mid-twentieth century.

Mistral is certainly the most famous casual script.

Almost all the aforementioned families are proportional in their style, (each character takes up space that is proportional to its width). This sub-family addresses each character width as the same, with narrower ones, such as i, just gain white space around them, sometimes resulting in weird appearances. Hence, Due to their nature and their spacing, they aren't advised as copy typefaces, since their mono spacing can bring unwanted visual imbalance to the text.

Courier is certainly the most known monospaced typeface.

They are the broadest category and are aimed at small copy to draw attention and rarely follow rules, spreading from every one of the preceding families and expressing every mood.

For example, Danube and Val are just two of the multitude that are out there:

Serifs, through their decorations, their widths, and in and out of their every sub-family convey old and antique/traditional serious feelings, even when more modern ones are used; they certainly convey a more formal appearance.

On the other hand, sans serif are aimed at a more modern and up-to-date world, conveying technological advancement, rationality, usually but not always, and less of a human feeling. They're more mechanical and colder than a serif, unless the author voluntarily designed them to be more friendly than the standard ones.

As said, they are of two types, and as the name suggests, the division is straightforward.

Vladimir is elegant, refined, upper class looking, and expresses feelings such as respect. Arizonia on the other hand is not completely informal but is still a schizophrenic mess of strokes and a conclusion less expression of feeling; I'm not sure whether I feel amused or offended for its exaggerated confidentiality.

Since they are different in aspect from each other and the fact that there is no general rule that surrounds and defines the Display family, they can express the whole range of emotions. They can go from apathy to depression, from a complete childish involvement and joy to some suited, scary seriousness business feeling (the latter definition is usually expression of some monospaced typefaces).

Like every other typeface, more specifically here, every change in weight and style brings in a new sentiment to the table: use it in bold and your content will be strong, fierce; change it to a lighter italic and it will look like its moving, ready to exit from the page.

As such, they take years to master and we advice not to use them on your first web work, unless you are completely sure of what you are doing.

Every font communicates differently, on a conscious as well as on a subconscious level; even within the same typeface, it all comes down to what we are accustomed to.

In the case of font color, what a script does and feel in the European culture can drastically change if the same is used for advertising in the Asian market.

Is the adjusting of space between two characters to achieve a visually balanced word trough and a visually equal distribution of white space.

The word originates from the Latin word cardo meaning hinge. When letters were made of metal on wooden blocks, parts of them were built to hang off the base, thus giving space for the next character to sit closer.

Tracking is also as called letter-spacing and it is concerned with the entire word—not single characters or the whole text block—to change the density and texture in a text and to affect its readability.

The word originates from the metal tracks where the wooden blocks with the characters were moved horizontally.

Tracking request careful settings: too much white space and the words won't appear as single coherent blocks anymore – reduce the white space between the letters drastically and the letters themselves won't be readable.

As a rule, you want your lines of text to be made of 50 to 75 characters, including dots and spaces, to achieve better readability. Some will ask you to stop your typing as soon as approximately 39 characters are reached, but I tend to differ.

According to kerning, especially on serifs, two or three character can clash together. Ligatures are born to avoid this; they are stylistic characters that combine two or three letters into one letter:

Leading is the space between the baselines of your text, while line-height adds to the notions and also to the height of ascenders and descenders. The name came to be because in the ancient times, stripes of lead were used to add white space between two lines of text.

There are many rules in typesetting (none of which came out as a perfect winner) and everything changes according to the typeface you're using.

Mechanical print tends to add 2 points to the current measure being used, while a basic rule for digital is to scale the line-spacing as much as 120 percent of your x-height, which is called single spacing.

As a rule of thumb, scale in between 120 and 180 percent and you are good to go (of course with the latter being used for typefaces with a major x-height). Just remember, the descenders should never touch the next line ascenders, otherwise the eye will perceive the text as crumpled and you will have difficulties to understand where one line ends and the other start.

This is important in a text because it helps the reader understand the order of the text, what's more important, what's regular text, what requires attention, and also with the use of descriptive titles it helps him skip entire parts of the text that are of no specific interest.

To achieve the aspect of a title and of a sub-title, different sizes and weights are used between the two parts. We generally prefer to triple the dimension of the actual text and go with the corresponding leading directly above it; if a subtitle is present, leading can be adjusted from 100 to 110 percent.

This book is written in English, actually aiming at the western cultures, which we tend to read and write from left to right; hence, the alignment of it's type follows the same direction.

It depends on your culture and whom your text is aimed to. It also depends on the general aesthetic that you're trying to achieve and usually compromises between the two needs to be fulfilled.

Scientifically speaking, centrally aligned text is the weakest from a readability point of view: your eye can't find a consistent starting and stopping point. So, every passage will automatically adjust every new line in an instant; it's a subtle but catastrophic step, since the focus will be shifted from the word to the general picture. People tend to be easily distracted when reading a text that is centrally aligned.

So, both left and right edges are good for typesetting; it depends on your language and aesthetics.

It's a term and a direct consequence of your alignment; it's the uneven vertical edge in a block of type.

A good rag goes in and out from the margin in small increments; while a bad, distracting one creates distracting shapes.

This can be managed by manually adjusting line breaks or by editing the copy:

It deserves a separate paragraph from the alignments, since every feature and every defect can be made visible with an aligned text; when the same text is justified, it tends to be exaggerated. It can be full, left, right, or centered with the terms referring to the alignment of the last line of text.

It's a common type of text alignment in print, where the spaces between words are stretched or compressed to align the left and right edges of the text equally.

This commonly gives birth to various issues, as a loose line where the space is just too much, or a tight one, where the text is too crumpled.

The centered one especially gives birth to rivers, which are gaps in the text that appear to run almost vertically and are bad for readability, since they distract the eye.

One good test for you to discover rivers in your typesetting is to take the paper or the text and rotate it by 180 degrees, turning it upside down.

Doing so will make the words and text less easy to be recognized by the brain, which will now concentrate more on the actual shape of your paragraph, instead of its meaning, which will allow you to see them better.