Standard form is a type of notation used to more easily represent very large or very small numbers.
It is often used by people such as engineers or astronomers who regularly have to work with numbers very small or very large numbers.
Take for example the number 5000, this could be rewritten as 5 x 1000 and again as 5 x 103. This last way of writing the number is called standard form.
The first part of the number must be less than 10 but greater than or equal to 1 and the second part of the number must be a power of 10.