Esperar

I have heard some people say _espere_ when meaning for someone to "wait," e.g., "Espere un momento, por favor." I thought that "you/he/she wait" was _espera_ and that espere (spelt esperé) was the preterit tense. Thanx.

"Espere" is a formal command. When you create a command in the "usted" form (as in, you're speaking formally or politely to someone), you take the usual present tense ending in the "usted" form (-a or -e) and switch to the opposite ending. So ... *esperar *means _to wait._ *Espera* means "You wait." (present tense, usted form) *Espere* means "Wait." (command, polite) Here's another example. *Correr *means _to run_. *Corre* means "You run." (present tense, usted form) *¡Corra! *means "Run!" (command, polite)