Bitmap based or Vector based?

I am confused about what software is used (bitmap or vector) in the making of anime characters and backgrounds. I’ve looked closely at anime and it looks like the backgrounds are made using bitmap software, but the characters with vector. Characters could be made with bitmap or vector software I suppose.

I noticed while watching anime that many times the camera zooms in on a character, yet the lines seem to stay the same thickness. This would suggest that characters are made with vector software. Of course, many times the camera will zoom in on backgrounds also.

Backgrounds and characters do not look like they were made with the same media in anime. I suppose it might be different from animation house to animation house. Perhaps there is no standard today.

Can anyone give me information on the subject of bitmap and vector based animation, as it pertains to character and background?