Both fonts and keyboards are needed to ensure transferability. A font may work fine on a personal computer, but when it is transferred to another machine (even one with the same font) it may not display correctly. The problem is that using only (non-Unicode) fonts simply "masks" the English keyboard. This means that when the letter "A" is typed the font displays an alpha. If the recipient does not have the correct "mask" (and sometimes even if they do) the text will not display correctly. However, when a foreign language keyboard is used, the layout of the input method is changed to the foreign language regardless of the font.
To illustrate the difference: type a word using a (non-Unicode) font such as SGreek, SPIonic, or SPTiberian. Now change the text to an English font such as Times New Roman or Arial. The text does not display correctly because it was a "mask" of English characters.
Now type a word using one of the recommended keyboards and fonts. Change the text to an English font as above. The characters change with the font because the display represents the actual letter rather than a "mask."
Unicode is a single set of coding standards which include all of the worlds known languages. Each character is assigned to an individual hex code (e.g. "A" = 41, "B" = 42, "a" = 61, "b" = 62, "a" = 03b1, "?" = 1f00). This makes it possible to create input methods for every imaginable language, thus allowing multilingual users the ability to type in different languages and easily transfer electronic material in many languages.
To learn more about Unicode and Biblical languages click here (.pdf) (article by Rodney Decker from http://www.NTResources.com). To learn more about the Unicode project and its history click here (from http://scripts.sil.org) and here (from http://www.unicode.org). To see the Unicode hex keys for biblical languages click the desired link: Greek monotonic (.pdf), Greek polytonic (.pdf), Hebrew (.pdf)).
The input method is the keyboard the computer uses when a key is typed on the physical keyboard. In single language computing the physical keyboard and the input method remain roughly the same (i.e. the letter “D” is typed on the physical keyboard and the computer receives the letter “D” via the input method), but in multilingual computing the input method can be changed while the physical keyboard remains the same (i.e. the letter "D" is typed on the physical keyboard and the letter "dalet" is received when using a Hebrew input method).
Simply put, monotonic Greek is used for Modern Greek while Polytonic Greek is used for classical Greek. Modern Greek uses a single diacritical marking (the "tonos") while biblical Greek uses multiple diacritical markings (breathing marks, acute, grave, circumflex, etc.). A polytonic keyboard is needed to use biblical Greek.
Although many fonts have Greek and Hebrew characters included, most do not have the range needed for biblical language use (e.g. Times New Roman includes monotonic characters, but not polytonic). The recommended fonts were designed (often by scholars) with biblical and classical languages in mind and include the characters needed for biblical language use.
In today's world, learning a language means learning to use a computer in that language. In the case of Biblical languages, where reading is sometimes the exclusive focus of instruction, this skill is perhaps even more important than in other language study, as computing is often the most interactive language skill they will regularly employ.
In this sense, computing plays a significant role in the identity-formation that inevitably and happily coincides with language instruction, as the student’s identity itself is formed and stretched by being opened to the thought-world the new language makes available. In the case of ancient languages, the intimate activities of speaking, writing, and listening are often not part of the language education; typing may be the most intimate language production in which the student engages; the addition of a Greek input method on the student's computer may be the most distinct badge that the student has to represent even to herself that this language has become and is becoming a part of her sense of self.
However, in this process, students find themselves in the middle of complex multilingual computing issues that they have not encountered elsewhere. these issues include those related to input method and font issues on the student's own computers (typically at the level of the operating system), issues presented within the word processor and other desktop applications (e.g. right-to-left support for Hebrew, complex diacritic support for both languages, etc.), and issues encountered in interaction with resources delivered via the Internet, typically within the web browser. A simple result of this situation can be seen in students use of transliterations or handwritten text when citing Greek and Hebrew texts in term papers, or—worse yet—avoiding recourse to original language material, instead relying on citation (and engagement) of translations.