Indentation is the change of the number of spaces in front of one or more lines of code. When you indent one or more lines you create a block of code which executed in an if or a loop command. All indented lines have to be equally indented. It is common to use 4 spaces to indent code.

A number with no fractional part. 

Includes: 

• the counting numbers {1, 2, 3, ...}, 
  
• zero {0}, 
  
• and the negative of the counting numbers {-1, -2, -3, ...}
  

We can write them all down like this: {..., -3, -2, -1, 0, 1, 2, 3, ...}

Examples of integers: -16, -3, 0, 1, 198

Repeated execution of a set of statements is called iteration. Because iteration is so common, Python provides several language features to make it easier.  The for and the while commands use the iteration procedure