A basic conversion specifier : Format « String « Python Tutorial

% character marks the beginning of the conversion specifier. 
Conversion flags, minimum field width, . (dot) followed by the precision.

Conversion flags may be -, indicating left alignment; 
                        +, indicating that a sign 
                      " ", indicating that a space should precede positive numbers; 
                        0, indicating that the conversion should be zero-padded. 


print 'Price of eggs: $%d' % 42 

print 'Hexadecimal price of eggs: %x' % 42 
from math import pi 
print 'Pi: %f...' % pi 

print 'Very inexact estimate of pi: %i' % pi 

print 'Using str: %s' % 42L 

print 'Using repr: %r' % 42L

5.10.1.String formatting is done with the string formatting operator, the percent (%) sign.
5.10.2.Formatted String
5.10.3.String format
5.10.4.A basic conversion specifier
5.10.5.use the string format operator ( % ), or put all of the substrings in a list, and using one join() call to put them all together
5.10.6.The syntax for using the format operator is as follows: format_string % (arguments_to_convert)
5.10.7.Format Operator Auxiliary Directives
5.10.8.String Formatting Conversion Types
5.10.9.print paired with the string format operator ( % )
5.10.10.Width and Precision
5.10.11.Signs, Alignment, and Zero-Padding
5.10.12.A minus sign (-) left-aligns the value:
5.10.13.A blank (" ") means that a blank should be put in front of positive numbers
5.10.14.a plus (+) means that a sign should precede both positive and negative numbers
5.10.15.String formatting.
5.10.16.String-formatting codes
5.10.18.The %e, %f, and %g formats display floating-point numbers in different ways, as the following interaction demonstrates:
5.10.19.Dictionary-Based String Formatting