Type on the Web: readability.
Readability is all about seeing shapes. Specifically, the shapes of letters (glyphs) and the larger shapes of the words they form. Anyone is spending much time reading from a computer screen knows that there is something "just not right" about the way letters are displayed. It is more than an issue of a typeface being represented faithfully (see a different article about that) and it gets down to whether the letterforms themselves are recognizable.
Because of the low resolution of a computer screen, many typefaces are simply not very readable on screen. There are just too few pixels available to build an easily recognizable letterform.
This is why sans serif fonts are most frequently used on the web. They are usually simple letterforms and the letters space well. To work around the problem of accessing readable fonts on the web, Microsoft and Apple (as suppliers of the predominant operating systems) have developed several faces that are designed specifically for low resolution (read: computer screen) use. For Microsoft these are Verdana, Trebuchet MS and Georgia and for Apple these are Lucida Grande and Geneva. In both cases, Arial, Helvetica and Times work well also, but they were not specifically designed for on-screen performance.
The size of the letter can sometimes compensate for its lack of readability in small sizes. For this reason, headlines tend to be the place where unusual typefaces are used for design purposes. But keep in mind that the face still needs to be on the readers computer. [see this article]
The Font Names being requested are (in order of preference): "Courier New", Courier, mono.
8 pixels — The Lioness - A controversy prevailed among the beasts of the field as to which of the animals deserved the most credit for producing the greatest number of whelps at a birth. They rushed clamorously into the presence of the Lioness and demanded of her the settlement of the dispute. “And you,” they said, “how many sons have you at a birth?” The Lioness laughed at them, and said: “Why! I have only one; but that one is altogether a thoroughbred Lion.” The value is in the worth, not in the number.
9 pixels — The Lioness - A controversy prevailed among the beasts of the field as to which of the animals deserved the most credit for producing the greatest number of whelps at a birth. They rushed clamorously into the presence of the Lioness and demanded of her the settlement of the dispute. “And you,” they said, “how many sons have you at a birth?” The Lioness laughed at them, and said: “Why! I have only one; but that one is altogether a thoroughbred Lion.” The value is in the worth, not in the number.
10 pixels — The Lioness - A controversy prevailed among the beasts of the field as to which of the animals deserved the most credit for producing the greatest number of whelps at a birth. They rushed clamorously into the presence of the Lioness and demanded of her the settlement of the dispute. “And you,” they said, “how many sons have you at a birth?” The Lioness laughed at them, and said: “Why! I have only one; but that one is altogether a thoroughbred Lion.” The value is in the worth, not in the number.
11 pixels — The Lioness - A controversy prevailed among the beasts of the field as to which of the animals deserved the most credit for producing the greatest number of whelps at a birth. They rushed clamorously into the presence of the Lioness and demanded of her the settlement of the dispute. “And you,” they said, “how many sons have you at a birth?” The Lioness laughed at them, and said: “Why! I have only one; but that one is altogether a thoroughbred Lion.” The value is in the worth, not in the number.
12 pixels — The Lioness - A controversy prevailed among the beasts of the field as to which of the animals deserved the most credit for producing the greatest number of whelps at a birth. They rushed clamorously into the presence of the Lioness and demanded of her the settlement of the dispute. “And you,” they said, “how many sons have you at a birth?” The Lioness laughed at them, and said: “Why! I have only one; but that one is altogether a thoroughbred Lion.” The value is in the worth, not in the number.
13 pixels — The Lioness - A controversy prevailed among the beasts of the field as to which of the animals deserved the most credit for producing the greatest number of whelps at a birth. They rushed clamorously into the presence of the Lioness and demanded of her the settlement of the dispute. “And you,” they said, “how many sons have you at a birth?” The Lioness laughed at them, and said: “Why! I have only one; but that one is altogether a thoroughbred Lion.” The value is in the worth, not in the number.
18 pixels — The Lioness - A controversy prevailed among the beasts of the field as to which of the animals deserved the most credit for producing the greatest number of whelps at a birth. They rushed clamorously into the presence of the Lioness and demanded of her the settlement of the dispute. “And you,” they said, “how many sons have you at a birth?” The Lioness laughed at them, and said: “Why! I have only one; but that one is altogether a thoroughbred Lion.” The value is in the worth, not in the number.
36 pixels — The Lioness - A controversy prevailed among the beasts of the field as to which of the animals deserved the most credit for producing the greatest number of whelps at a birth. They rushed clamorously into the presence of the Lioness and demanded of her the settlement of the dispute. “And you,” they said, “how many sons have you at a birth?” The Lioness laughed at them, and said: “Why! I have only one; but that one is altogether a thoroughbred Lion.” The value is in the worth, not in the number.