Integers are numbers without a decimal point. Contrary to other programming languages, they can be defined with leading zeroes and remember them.

Examples:

a = 5
b = -4003
c = 000
d = 000005

To wheat your appetite, here is an example which takes away some things explained later, but illustrates the point. Imagine you want to load 10 PDB files, named Model001 to Model010.

As a C programmer, you would type:

char filename[9];
int i;

for (i=1;i<=10;i++)
{ sprintf(filename,"Model%03d",i);
  LoadPDB(filename); }

As a Python programmer, you save a lot and earn percents and a mysterious '11':

for i in range(1,11):
  LoadPDB("Model%03d"%i)

As a Yanaconda programmer, your life is easy:

for i=001 to 010
  LoadPDB Model(i)