Standard form refers to the simplest and clearest representation of a number, formula or equation. The specific standard form of a term or equation depends on what the subject is.
The standard form of a single number is used to represent large numbers clearly. They are written so that there is a single number in the one's place, multiplying it by 10 to some exponent. For example, 5326 is written as 5.326*103 in standard form.
For an equation, variables are expanded as much as possible and all terms are taken to the left side of the equation. For example, x2=7 is equal to x2-7=0 in standard form.