Bricks are rectangular blocks of baked clay used for building walls, which are usually red or brown. Brick is the material made up of these blocks.

If you say that someone is a brick, you mean that they have helped you or supported you when you were in a difficult situation.

If you are banging your head against a brick wall, what you are saying or doing is not having any effect although you keep saying or doing it.

If you hit a brick wall or come up against a brick wall, you are unable to continue or make progress because something stops you.

You can use bricks and mortar to refer to houses and other buildings, especially when they are considered as an investment.