Why is welded wire mesh used in concrete?

IT helps strengthen the concrete and prevent cracking

But please note usually the "welded wire mesh" used in concrete is named reinforcing mesh, its wire is ribbed. And the wire of welded wire mesh in industry usually is plain, it used for fence panel, floor heating system and so on.

The following are reinforcing mesh and welded wire mesh link.

dingzhenfence.com/product/Welded_Wire_Mesh.html

dingzhenfence.com/product/Welded%20Wire%20Mesh