Why to use html codes?

There are several operating systems in the world of computers. These systems are nothing that special programs running immediately after turning on the computer, and are in charge of giving "life" to your machine.
Alongside these programs, computers loaded into memory special tables that match the characters having your keyboard and some more that are not in it, but you can type on screen by other means. These tables, unfortunately, are not always the same, and vary from one system to another, from one brand of computer to another, and of course, from one language to another. For example, do not look the same letters with accents from a PC from a Macintosh, or UNIX terminal, if we write them directly from the keyboard.

Since HTML is intended as a universal language, and that a page should look like the creator wants, regardless of whether this is a computer that "speaks" in English or Spanish, or has this or that operating system was created a character table "conflicting" (actually they all are, but generally only used for special characters) that are written with a code instead of pressing the key that contains it directly.

For example, our world reviled among "Ñ" is written:

        Ñ ​​or Ñ
This will be done with all characters other than letters of the alphabet (uppercase and lowercase), numbers and a few signs, such as point, comma, hyphen, and a few others. This set of characters, common to all systems, is called the ASCII code, and since then we have to encode all accented letters, ñ, cedillas, etc., Etc.
The index will find a table with all the characters are also letters, but these will be useful only if you need to write texts somewhat rare.

As you can see, the table has a column with the desired character followed by its code number in decimal, a description of the character and after a short (a sort of alias) that is common to come to memorize, and things short, they help. Not everyone has the short name, and these have to write to the code number. In some special cases which will later have to write the numeric codes in hexadecimal base (the Windows calculator has a converter).

Generally, you can type directly from keyboard all with no alias in the table, those that do will usually have problems in different systems that has been used to write the document. If you write HTML you can rest assured that they will only be used as local files on machines similar to yours, you will not need to complicate your life, but if your pages will reside on a WWW server, any machine can access them, and their appearance will not be appropriate for some.

There are many special editors to write HTML, and most of them have tools to automatically convert special characters to their corresponding code. There are also packages of "macros" to do the same with word processors like Word or Word Perfect.
http://sestud.uv.es/manual.esp/coditext.htm