Unless you're an incessant stickler for grammatical details, chances are you make dozens of errors each day in the way you use English. And if you're like many native speakers of English, you might not notice until you're told that a sentence such as "each of them brought their pencils" is enough to make some grammarians grit their teeth.
Since language errors are so common in English, it shouldn't come as a surprise that Spanish speakers make their share of mistakes too when speaking their language. They generally aren't the same mistakes you're likely to make when speaking Spanish as a second language, but they are probably every bit as common in Spanish as they are in English.
Following is a list of some of the most common errors made by native speakers; some of them are so common they have names to refer to them. (Because there isn't unanimous agreement in all cases about what is proper, examples given are referred to as nonstandard Spanish rather than as "wrong." Some linguists argue that there's no such thing as right or wrong when it comes to grammar, only differences in how various word usages are perceived.) Until you are so comfortable with the language that you have reached fluency and can use a style of speech appropriate for your situation, you are probably best off avoiding these usages — although they are accepted by many speakers, especially in informal contexts, they might be viewed as uneducated by some.
Dequeísmo — In some areas, the use of de que where que will do has become so common that it is on the verge of being considered a regional variant, but in other areas it is strongly looked down on as being the mark of an inadequate education.
- Nonstandard: Creo de que el presidente es mentiroso.
- Standard: Creo que el presidente es mentiroso. (I believe the president is a liar.)
- Nonstandard: La escribí una carta. No lo escribí.
- Standard: Le escribí una carta a ella. No le escribí a él. (I wrote her a letter. I did not write to him.)
- Nonstandard: Voy a enseñarle a mis hijos como leer.
- Standard: Voy a enseñarles a mis hijos como leer. (I will teach my children how to read.)
- Nonstandard: Conocí a una persona que su perro estaba muy enfermo.
- Standard: Conocí a una persona cuyo perro estaba muy enfermo. (I met a person whose dog was very sick.)
- Nonstandard: Habían tres casas.
- Standard: Había tres casas. (There were three houses.)
- Nonstandard: No conozco al hombre viviendo con mi hija.
- Standard: No conozco al hombre que vive con mi hija. (I don't know the man living with my daughter.)