Saber and Conocer

Saber vs Conocer / Pedir vs. Preguntar

In Spanish, there are two verbs that express the idea "to know." These two verbs are "saber" and "conocer." The verb you choose depends upon the context in which it is used. These verbs are not interchangeable.

To express knowledge or ignorance of a fact or information about something, use "saber."
Juan sabe donde está María.
Juan knows where Maria is.
Yo no sé tu número de teléfono.
I don't know your telephone number.

To say that one is or is not acquainted with a person, a place, or an object, use conocer.
Yo no conozco a María.
I don't know (am not acquainted with) Maria.
Alberto y Alfredo conocen Madrid.
Alberto and Alfredo know (are acquainted with) Madrid.

To express knowledge or ignorance of a subject or learning discipline, use saber or conocer, depending upon the context.
Juan no sabe nada de inglés.
Juan doesn't know any English.
Él sabe matemáticas.
He knows mathematics.
Juan conoce la literatura española.
Juan is familiar with Spanish literature.

To express knowledge or ignorance of a skill, or how to do something, use saber + infinitive.
María sabe conducir.
Maria knows how to drive.
No sé nadar muy bien.
I don't know how to swim very well.

To say that you know something by heart, use saber.
María sabe los verbos irregulares.
Maria knows the irregular verbs (by heart).
Ella no sabe la letra de esa canción.
She doesn't know the words to that song.

The situation with regards to the correct use of saber and conocer can be summarized as follows:
to know a fact, to know something thoroughly, to know how to do something
to be acquainted with a person, place, or thing

The same sort of situation exists with respect to the two Spanish verbs pedir and preguntar. They both mean "to ask" but they are not interchangeable. Fortunately, the rules for using them are a bit more straightforward:
to ask for, or request an object, service or favor
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