What is the purpose of having check boxes beside the contact folders?

What is the purpose of having check boxes beside the contact folders?
I though the creating of folders was just for personal organization of all your emails.
If checked or unchecked what affect does this have?

It allows you when you go to Contacts to then “just see / display those specific contacts” (all in one view) and not all the other contacts. eg: You might check 2 or more specific contact folders to then only display those contacts when you open contacts.

(Example where i only want to display contacts from 3 contact folders rather than all my Contacts.

Thanks cyberzork for the clarity. I thought checking or unchecking folders would control what email addresses would be available for auto suggestion in the To:

I thought checking or unchecking folders would control what email addresses would be available for auto suggestion in the To:

Ah ok.

You can also though use these contact folders for selecting recipients (manually) in the To:, line via clicking the To: next to Compose and then clicking the “Contacts” Dropdown on the right, and lastly “Selecting the Folder”. You will then only see those specific folder contact recipients and “dbl-click them to add into the To: line below” as in my Gmail account contact folders below. So might be useful for you.

I was referring to auto suggest email addresses in the drop down of the To: field. I have a folder with email addresses I use on a daily basis and a folder with addresses that I may use once a year, so I want just the frequently used addresses to auto suggest…to clear clutter. If and when I need to access the rarely used addresses I’ll manually go into the appropriate folder…thanks for your feed back.