SMQ1 and SMQ2

Hi all,

Can someone please explain the role of SMQ1 and SMQ2 in XI system.

When data somes from a source system which queue does it first go to? In sxmb_moni which queue so we exactly see (smq1 or smq2).

What is the relation between Integration Server and the Messaging System?

And what is the relation between Integration Server and Adapter Framework?