I've heard that to make communication between two vlans possible, you need a layer 3 device.
Suppose that I connect two layer 2 switches via trunk link passing two vlans 10 and 20 on it. Both switches have some devices of both vlans connected to it's interfaces. If I configure int vlan 10 and int vlan 20 ip addresses on both switches, then I will be able to ping every end host devices from any end host device regardless of their vlan subnet. So, isn't this an example of inter vlan communication where I didn't use layer 3 device? So, why we need layer 3 device to make two vlans communicate with each other? I tested this setup via packet tracer.
