Type anatomy, Typefaces, Fonts, etcetera...
To be able to use type correctly we need to start out by learning about the construction of type in the Latin alphabet. This is also often termed as the anatomy of type and has its foundations in an era that came before the printing presses and typography as we know it today: Before printing, books used to be written by hand using a goose feather quill. This quill would be cut at a 45 degree angle and when a right handed person held such an ink filled quill in their hands and started to write, all lines that ran in angles from top left to bottom right would be thick, all lines running in angles from top right to bottom left would be narrow, all perpendicular strokes would be medium-thick and all horizontal strokes would be medium-narrow (link 01). When the first roman (latin) typefaces were created this same rule was applied to their design. Thus when you look at a serif typeface, such as Times New Roman, you can see very clearly that the letter carries various thicknesses in different parts. In the 20th century, when sans serif typefaces were created again the same rules were applied (link 02) although in sans-serif typefaces this variation is far less obvious. However if you do look carefully at a sans serif typeface, such as Arial, you will see the differences in stroke width quite clearly. And this brings us to two very important mistakes commonly made by contemporary would-be designers with no awareness of the historic reasons behind type anatomy (link 03): The computer enables us to condens typefaces. However typefaces that are condensed "by hand" will have horizontal lines that are wider than the perpendicular lines. The correct thing to do is to use fonts that are specifically designed as condensed fonts. Similarly slanting typefaces backwards to create italics is a big no-no (link 04). Try taking a quill and drawing a "backwards" italic. It simply won't work or will look extremely ugly, if you do in fact manage to pull it off. Always use proper italic fonts to denote italics.

Typefaces and Fonts
Although the term "Font" is used to describe typefaces as well as the individual fonts here is the correct meaning of these terms:
Typeface: Is the entire family of fonts. Thus when I say Helvetica (Swiss for PC) or Bodoni I mean all the fonts that comprise that family, such as bold, light, italic, condensed and so on.
Font: Is the individual member of the typeface family. Thus when we say Bodoni Bold or Swiss Light Extended we are referring to that one particular font as opposed to the entire family of the typeface (link 01).

Major Type Categories
The most basic way in which typefaces can be categorised are the Serif's and Sans-serifs. Serif typefaces were initially created by the Romans. The little "shoes" added to the ends of the strokes were meant to keep the chisel from slipping while carving letters into stone. Later this beautiful system of designing type was adapted to book design, initially as uppercase letters only (link 01). In the late renaisance type designers such as Garamond and Bodoni developed the full lowercase typefaces to be used with the printing press, which we use even today. The final rules of type design were established by Geofrey Tory, upon the comission of the Golden King Louis XIV. Tory wrote and designed the penultimate typography book of all times; Champs Fleury (link 02).

Serif typefaces can be sub categorised into hard, medium and soft serifs (link 01), depending on the shape of their "shoes". A general rule of thumb is that the harder the serif the better a typeface will look in larger point sizes. Soft serifs are excellent for body text (small point text of considerable length, arranged into columns) since the soft serifs provide an excellent baseline which greatly fascilitates reading of lengthy texts. Thus, a lot of books and magazines will use Garamond as body text (link 03).

Although generally suited to serious, "timeless" design, such as corporate work for institutions like banks, major companies and the like, serif typefaces can be used in contemporary design to great effect, given proper context and handling (link 04).

Sans-serif typefaces are a relatively new addition to typography, only having come into existence in the first quarter of the 20th century, at the instigation of the Bauhaus School. The Bauhaus designers considered the serifs as decorative items, and thus superfluous, maintaining that type should be straight, ending in straight corners. The typeface Futura (link 01) was designed in 1926 by Paul Renner, giving us the best developed example of what the Bauhaus designers were concerned about. Futura is widely used today, although it does have very characteristic overtones of early 20th century design.

However the most beautiful as well as widest used sans-serif typeface, Helvetica (Swiss) came into being in 1945 and was designed by Swiss designer Max Miedinger (link 02). An entire graphic design school, the only one that is named after a nation, i.e. Swiss Style was developed around this gorgeous typeface. In the years to follow many variations and adaptations of Helvetica were designed. Arial, which is an even more elegant and simplified version, does not have as wide a family but is nonetheless one of my personal favorites. Franklin Gothic is yet another beautiful variation of Helvetica (link 03).

All typefaces, be they serif or sans serif, show the variation in width mentioned at the begining of this link. However certain sans serifs do this to a greater degree than others and thus sans-serif typefaces can be subdivided into 2 categories. These are the demi-serif typefaces and the proper sans-serifs. A good example to the demi-serifs is Gill Sans (Humanist on the PC) (link01). Demi serif typefaces are sans-serif in that they have no "shoes" at the stroke endings. However they show a greater diversity in stroke width than regular sans serif typefaces thus falling somewhere between serif and sans serif fonts, showing characteristics of both.

Other major Type categories
Scripts are based upon handwriting, again emulating the characteristics of the goose feather quill, mentioned at the begining of this link (link 01). Script typefaces were designed during the Renaisance and especially the Baroque era saw the fanciful addition of scroll borders to scripts (link 02). Script typefaces will need a definite context with which they can be used: Romantic, elegant subjects are particularly suited to these typefaces. Just like serifs, script typefaces can be used to great effect in contemporary design (link 03), given correct context and handling.

Brush Script Typefaces are a contemporary version of the regular script fonts. My advice to any young designer starting out, is to stay away from these typefaces altogether, until reaching a solid understanding of designing with type. Although there are extremely beautiful brush scripts (link 01) around, there are also even more truly horrifying scribbles (link 02) out there that should be avoided at all costs. Unfortunately some of the better known brush scripts do tend to fall into this category. Furthermore, brush script typefaces need a definite context and content within which they can be used; that being an informal one implying intimacy and warmth.

Bitmap/Screen Typefaces
A very recent addition to typography are the screen fonts that are designed specifically for computer viewing, especially web design. These typefaces, in their intended application, can only be used at a resolution of 72 pixels per inch and then only at the proper point size and in aliased form. Thus Mini 7 (link 01) will look wonderfully sharp, aliased at 10 points exactly on a bitmap document set at 72 pixels per inch, but will completely fall apart if the point size or the resolution is off. However I find bitmap typefaces extremely effective when used outside of their actual intention; in very large point sizes that accentuate their "zig-zag" contours (link 02, 03).