A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
(if anybody should ask you) - RS: As the Wiki does not accept single-letter names in the URL, you can always find them in this page :^) AMG: No longer true, the Wiki happily accepts single-letter names in the URL.
AM I am a bit surprised that RS did not remark on the title, so I will do it (yes, it is a bit pedantic, I know :)).
First of all: "the" alphabet? Hardly. Besides the above Latin alphabet the world has at least Arabic, Hebrew, Greek, Cyrillic and Gaelic alphabets too. Then, most European languages that use the Latin alphabet add their own letters to the 26 above, for instance Danish has an "o" with a "/" and Spanish the "n" with a "~". You may say, these are variations on existing letters. True, but German has the doppelt-S, Icelandic has eth and thorn, as the English language used to as well (a couple of centuries ago, and where is the yogh now?). And the alphabetic ordering sometimes differs as well: Dutch considers the combination "ij" to be a single letter, rivaling in the ordering with "y". Swedish, if I am not mistaken, puts the "aa" after the "z", which incidentally foils the intention of the namegiver of an insect called "zyzzix", who wanted the word to be the last in any dictionary.
So, "the" alphabet? Hardly. - RS: I just found this page, which just enumerated [A-Z], and thought of how to make it at least somehow useful. See collation for some more alphabet info.
wdb The German ß (Doppel-s or ß) is a ligature (typographic two-character combination) of a "long s" and a "round s" -- depending of some rules of German Fraktur writing rules those goddammy (sorry 1000x) days. So, it is not one, but two letters, both of them fitting to the alphabet.
The name "alphabet" descends of the first two letters of Ancient Greek "alpha", "beta", ..., such that it fits to all descendors of this letter system. Including the Cyrillic. Not-including the Hebrew and Arabic, and Gaelic (which I never have seen, but it obviously descends from Celtic culture). - RS notes that the Hebrew alphabet starts with "alif beit", and the Arabic with "alif ba"...
"The" alphabet? In our context (all of us "speaking" English as lingua franca of CS): yes, why not?
AM There are many ligatures in printing, but very few in handwriting, the Doppelt-s is one of them.
The Gaelic alphabet may be just a variation on the Latin one - more round letters, You will find them in the streets of Ireland, for instance. Duoas Ancient Gaelic writings consisted mostly of variations on tangential strokes about a continuous line in an alphabet we now call Ogham [L1 ]. Since the language was forbidden for so many years (with English in lieu) modern writings naturally take from the English forms. But as Gaelic is a logophonemic language a lot of diacritics were added to aid in assigning letter classes (for pronunciation :-@ --though that doesn't help non-gaelic persons. 'Duoas' is actually an "I can read that" version of Dúthomhas for the rest of the world. If you can say the first you are probably pretty close to the second. :-) )
And I just wanted to oppose the idea that these 26 letters comprise the whole tale :).
DKF: FYI, the question of what is the alphabet really does depend on the locale. For example, Swedish considers ä, å and ö to be distinct letters from a and o, and yet German considers ä and ö to be minor variants of a and o respectively.