giantsfan3:
Are there any reasons why a DC power jack/connector (for Wall adapter) is provided on the Arduino boards?
It appears to me that it wouldn't have any advantage (in sourced current, or in convenience) that isn't already provided by either a USB cable from a computer or else a USB wall charger cable.
Ummm... so you can use a variety of power sources,
eg. Batteries.
Or power supplies with other voltages then 5V (the jack has a voltage regulator).
Or...