Basically zram is compression inside ram

It just compresses your ram contents so you can fit more stuff in memory at once

There are two types of computer memory that fundamentally matter on the consumer level:

• memory, as in RAM, which is like short-term memory in people, or how much you can think about at once. It is blanked when the computer restarts. It is very fast.
• drive storage, as in hdd or ssd space. This is like long-term memory or overall knowledge capacity, and persists across boots. It is comparatively slow.

Solid state disk storage, and in particular some SD cards, can be vulnerable to excessive writes.

Ram, however, is not impacted by the number of uses.

A swap file works like this: When memory gets full, you move the least-used parts onto the swap file.

A normal swapfile is on-disk. When memory gets close to full, the system moves some onto the (much much slower, like 10-1000x) on-disk swapfile.

Zram swap creates a compressed swapfile out of your free memory. A file in linux does not have to be on a hard disk/ssd, it just has to look and quack like a file. When memory gets close to full, the system copies some onto the in-memory compressed file. This is very fast, but uses some cpu. It doesn't touch your drive storage.