Alphabets, or phonemic alphabets, are sets of letters, usually arranged in a fixed order, each of which represents one or more phonemes, both consonants and vowels, in the language they are used to write. In some case combinations of letters are used to represent single phonemes, as in the English sh, ch and th.
The Greeks created the first phonemic alphabet when they adapted the Phoenican alphabet to write Greek. They used a number of Phoenician letters that represented consonant sounds not present in Greek to write Greek vowels.
The word alphabet comes, via the Latin word alphabētum, from the Greek word αλφάβητος (alphabētos), which itself comes from the first two letters of the Greek alphabet, α (άλφα/alpha) and β (βήτα/beta). The names of the Greek letters were based on Phoenican letter names. The first two letters of the Phoenican alphabet are 'āleph (ox) and bēth (house).
The best-known and most widely-used alphabets are the Latin or Roman alphabet and the Cyrillic alphabet, which have been adapted to write numerous languages. Most other alphabets are used for a single language or just a few languages.