what is ?client&channel=mac_bm Macbook Pro
-Safari, preferences, general, new window opens with - Favorites.
-File, new window.
I see Favorites, right click on the google icon, click on edit address.
What I see here is https:/www.google.com/?client&amp;channel=mac_bm. 
What is this? 
Even when I edit the address it will go back to this one.
How is this extra part starting with the ? even added on in the first place?
It is just telling Google the type of "computer" you have.

The client is you and mac is the type of computer you have.