As a Spanish verb is conjugated, changes in its spelling may alter the way the word is pronounced, so additional spelling changes are necessary to ensure that the resulting pronunciation of the word matches the pronunciation of the original. Basically, Spanish is a phonetic language, so what you see is what you get (or, more precisely, what you see is what you say or hear). The following eight groups give these spelling changes some sense of logic:
Group 1: Soft g changes to j in front of an -o or an -a ending.
Group 2: Hard gu changes to g in front of an -o or an -a ending.
Group 3: Hard qu changes to c in front of an -o or an -a ending.
Group 4: The c in -cer or -cir verbs, when preceded by a consonant, changes to a z in front of an -o or an -a ending.
Group 5: The c in -cer or -cir verbs, when preceded by a vowel, changes to zc in front of an -o or an -a ending. (This spelling-change rule is not dictated by pronunciation reasons, but it still falls under the category of a spelling change rule.)
Group 6: Hard c changes to qu in front of an -e ending.
Group 7: The letter z changes to c in front of an -e ending.
Group 8: Hard g changes to gu in front of an -e ending.
Groups 1 through 5 affect the present tense; here some examples of each group.
| yo | escojo |
| tú | escoges |
| él/ella/ello/uno | escoge |
| usted | escoge |
| nosotros | escogemos |
| vosotros | escogéis |
| ellos/ellas | escogen |
| ustedes | escogen |
Another verb in this group is proteger (to protect).
| yo | distingo |
| tú | distingues |
| él/ella/ello/uno | distingue |
| usted | distingue |
| nosotros | distinguimos |
| vosotros | distinguís |
| ellos/ellas | distinguen |
| ustedes | distinguen |
Two other verbs in this group are conseguir (to attain) and seguir (to follow).
| yo | delinco |
| tú | delinques |
| él/ella/ello/uno | delinque |
| usted | delinque |
| nosotros | delinquemos |
| vosotros | delinquís |
| ellos/ellas | delinquen |
| ustedes | delinquen |
This verb stands alone — no other verb follows its example.
| yo | convenzo |
| tú | convences |
| él/ella/ello/uno | convence |
| usted | convence |
| nosotros | convencemos |
| vosotros | convencéis |
| ellos/ellas | convencen |
| ustedes | convencen |
Another verb in this group is vencer (to defeat/conquer).
| yo | conozco |
| tú | conoces |
| él/ella/ello/uno | conoce |
| usted | conoce |
| nosotros | conocemos |
| vosotros | conocéis |
| ellos/ellas | conocen |
| ustedes | conocen |
Other verbs in this group are conducir (to drive), producir (to produce), traducir (to translate), crecer (to grow), ofrecer (to offer), and pertenecer (to pertain).
“But what about Groups 6 through 8?” you ask. Those groups (along with Groups 1 and 2, pulling double duty) deal with the subjunctive mood, which you use to express wish, desire, and/or supposition.