The Spanish writing system or orthography is noteworthy for the transparent relation between the letters of the alphabet and the phonemes of Spanish, although this does assume a Castilian model of pronunciation as opposed to, say, an Andalusian one or a Chilean one.
The table below shows the letter or letters of the alphabet that correspond to each of the Spanish phonemes.
Note that a capital letter between slashes denotes an archiphoneme, which occurs in contexts of neutralization. In such cases, Spanish uses the letter r for vibrants (i.e. /R/) and the letter l for laterals (i.e. /L/); among the nasals (i.e. /N/), it uses m for bilabials and n in the remaining cases. This latter circumstance explains why words like Enrique, tengo, ancho and confuso all have n as their nasal despite the fact that in each case the precise sound is different, viz. [n], [ŋ], [ɲ] and [ɱ].
|/i/||i, -y||/x/||j; g (before i or e)|
|/t/||t||/N/||n; m (before bilabial cons.)|
|/k/||c; qu (before i or e)||/l/||l|
|/g/||g; gu (before i or e)||/ɾ/||r|
|/θ/||z; c (before i or e)||/R/||r|
The letter h is silent in all cases and so corresponds to no phoneme.
The letter x corresponds in principle to the sequence /ks/, as in [ˈeksito] éxito ‘success’. When this sequence forms a cluster with a following consonant, there is a tendency for /k/ to be weakened or elided, as in [estɾaŋˈxeɾo] ‘foreign’. This is a variable process, however, and [ekstɾaŋˈxeɾo] would also be possible, particularly in more careful speech.