Answer 1

A container control contains 1 or more child controls.
Example, When you fill a form(you can say,you are creating a new e mail ID),You get many textboxes in a single page. That page can be called as a conatiner and the textboxes(and buttons,radio buttons etc) are child controls.
P.S-Lets say you completed the form, and now the last part is left-the human​ CAPTCHA Verification.Here it(remember its a child control as well)is in another container control which is a box around it. SO thats a container for captha , but a child for the main page.