**List comprehensions** are a concise way to create lists. They are used to create a new list by iterating over another list. 

# Syntax
It consists of square brackets containing an expression followed by the "for" keyword. The result will be a list whose results match the expression.

The basic syntax is :
```python
newlist = [output_expression(x) for x in oldlist if conditional(x)]
```

The above syntax is explained through the illustration below:



# Parameters
The list comprehension basically consists of four parameters. 
- **Output expression:** Defines the output of the list
- **Oldlist:** Defines the list which is to be traversed
- **Conditional/predicate:** Defines a condition on variable x. This is an optional parameter.
- **Newlist:** Save the result of list expression in the newlist

# Example 1
The following code creates a list containing the square of numbers:

l1=[] #declare an empty list
l1=[x*x for x in [0, 1, 2, 3]] #store the result of list comprehension in l1
print (l1)#print the list 


# Example 2
The following code uses a predicate expression and stores only the square of those numbers in the list which is divisible by 2:

l1=[] #declare an empty list
l1=[x*x for x in [0, 1, 2, 3] if (x%2==0)] #store the result of list comprehension in l1
print (l1)#print the list 


What is list comprehension in Python?

A concise way to create lists by iterating over another list with optional conditions.