system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do bricks work?

Are they structural to making buildings stay up? Or just an attractive exterior? Are there different types? How tall can a brick building be before the bottom bricks break under the weight of the bricks above them?
gpt
They used to be structural but today most cases they are more for the thermal mass and the style.

Most buildings are wood/steel/concrete structurally today with the brick layer is only an outer layer that provide: 

- Mass to help control temperature
- Protection from the elements
- Style

You can identify that a brick wall is of this type because all the bricks will be lengthwise ("wide") across the entire wall (usually).

In older buildings they do have a structural function. In these cases a brick wall isn't just one layer of bricks but several layers stacked and interlocked together. You can identify these because every few bricks in height you will see a row of "thin" bricks. These are bricks layed inward so that the outer layer will interlock with the next layer of bricks.

The total height they can support is based partly on the thickness of the wall (something like a height of no more then 20 times the walls width at the base), though it's fairly rare to see a building of this type taller then 10 stories as it becomes increasingly more complicated to make a brick building taller without another supporting structure.