print function help percentage and slash (multiple variables)

[leodavinci1990]

What is the function of adding a back slash in the following code after the percentage operator? I am testing it without the slash and it gives the same result.
Please note that I know I am not currently using the best practice for string formatting (format function method) in this example.

def distance(a,b):
    """ a and b are tuples. Finds the distance between them """
    return ((a[0]-b[0])**2+(a[1]-b[1])**2)**0.5
p1=(10,10)
p2=(10,20)
p3=(20,20)

print("The distance between %s and %s is %0.1f."%\
(str(p1),str(p2),distance(p1,p2)))
print("The distance between %s and %s is %0.1f."%\
(str(p1),str(p3),distance(p1,p3)))