Friday

Today I was working python lessons and I like this tutorial that help you to average a certain of number in this application I can put the many number. This is the application codes:

count = 0
usum = 0.0
number = 1

print("Enter 0 to exit the loop")
while number != 0:
    number = float(input("Enter a number: "))
    if number != 0:
        count = count + 1
        usum = usum + number
print("The average was:", usum / count)

I I don't understand why the exclamation (!) sing in the lines (while number != 0:) and (if number != 0:)