Division
Division is splitting into equal parts or groups.
It is the result of "fair sharing".
Example: there are 12 chocolates, and 3 friends want to share them, how do they divide the chocolates?
12 Chocolates  12 Chocolates Divided by 3 

Answer: 12 divided by 3 is 4: they get 4 each.
Symbols
÷ / 
We use the ÷ symbol, or sometimes the / symbol to mean divide: 12 ÷ 3 = 4 Let's use both symbols here so we get used to them. 
Opposite of Multiplying
Division is the opposite of multiplying. When we know a multiplication fact we can find a division fact:
Example: 3 × 5 = 15, so 15 / 5 = 3.
Also 15 / 3 = 5.
Why? Well, think of the numbers in rows and columns like in this illustration:

So there are four related facts:
 3 × 5 = 15
 5 × 3 = 15
 15 / 3 = 5
 15 / 5 = 3
Knowing your Multiplication Tables can help you with division!
Example: What is 28 ÷ 7 ?
Names
There are special names for each number in a division:
dividend ÷ divisor = quotient
Example: in 12 ÷ 3 = 4:
 12 is the dividend
 3 is the divisor
 4 is the quotient
But Sometimes It Does Not Work Perfectly!
Sometimes we cannot divide things up evenly ... there may be something left over.
Example: There are 7 bones to share with 2 pups.
But 7 cannot be divided exactly into 2 groups,
so each pup gets 3 bones,
but there will be 1 left over:
We call that the Remainder.
Read more about this at Division and Remainders
Exercises
Try these division worksheets.