According to
Saussure, an alphabet can be understood as a sign system in which letters play
the role of signs: each letter has particular visual characteristics and is
associated with particular sounds. (Allington & Hewings,
2012)
Languages use different writing systems, such as
Egyptian hieroglyphs in ancient Egypt, Cuneiform
script, invented by the Sumerians, and the
Canadian aboriginal syllabics. According to Hanley, English employs an
alphabetic writing system in which letters (graphemes) represent the
spoken sounds of words (phonemes). (Hanley, 2010)

The English
language uses an alphabetic writing system. A writing system is also known as orthography.

English orthography is said to be opaque, it requires a lot of effort to
understand. Acquiring English requires extensive practice. In the case of
languages with transparent orthographies, such as Spanish, Italian, Finnish,
and Turkish, a grapheme (letter) represents the same phoneme (sound) which the
grapheme is associated with. However, English applies a contrasting rule. There
are two explanations which answer the question why English applies an opaque
orthography that is difficult to acquire. Firstly, the spelling of a word
remains frozen to its original form even when changes occur to its
pronunciation. An example for frozen spelling can be found in the word Autumn,
in which the last sound n is silent. Secondly, when words are imported
from other languages through the process of borrowings, the spelling remains
frozen to its derived form from the original language. For example, the word Genre
imported from the French language meaning type or kind. Unlike
transparent orthographies in which the spelling is reformed in order to match
its spoken form.