what is the difference between "pensar en" and "pensar de"? give examples, please.
"Pensar de" - "to think of" as in "to have the opinion about something"
What do you (familiar) think of Lady Gaga? ¿Qué piensas de Lady Gaga?"
What do you (formal) think of (insert sports team name here)?/How about them (insert sports team name here)? --- ¿Qué piensa usted de los...?
"Pensar en" - "to think of" as in "to have preoccupy one's mind" --- basically, someone or something you are thinking about!! Use "pensar en" when talking about having your thoughts be focused on something/someone.
I think about my mom every day. Pienso en mi mamá cada día.
One of my favorite Spanish songs, "Niña Bonita", says "Y yo solo pienso en ti", meaning, "And I only think of you".
"Pensar en" means "to think about", as in pondering something.
"Pensar de" means "to think of", as in getting an idea.
The two phrases are used pretty much the same way as the corresponding phrases in English.