What does this mean in the top corner on the left

[Chris Mooney1]

New to iPhones, wondering what this is in the top corner on the left

 

[EdwinG]

Welcome to iMore and congratulations on your new iPhone

That button indicates that you can go back to the previous view (or "window"), which in this case is a list of received SMS/MMS/iMessages. The 105 indicates that you have 105 unread messages.

When you have a moment, feel free to introduce yourself here: New to the Forums? Introduce Yourself Here! (imore.com)

And I hope you enjoy your new device

 

[Annie_M]

Welcome to iMore!!!

 

[Spencerdl]

Welcome to iMore