Your floating point data (Decimal Data) can be represented either via Single data type of Double data type. The basic difference being the precision between the two types. Now contary to the name, its not the precision that doubles. Its the number of Bits used in your computer memory for storing the data that doubles. Single datatype uses 32 bits of memory whereas Double uses 64 bits of memory. With higher precision, you get better accuracy but at the cost of memory and processing. This being a nutshell summary, you can google out for details. Hope this helps!