Change needles?

Hello all-- I am very new to knitting and have a question. I was reading some patterns today and a couple of them stated to switch needles during the knitting process. Does this mean to take stitches off and switch them literally? And how do you do that gracefully without loosing any stitches?
thanks for any advice!

Usually you just knit onto the new needle size from the old.

Ditto Debi

I get it! Thanks so much!!! :woot: