Float64 is a data type used in programming and computer science to represent decimal numbers. It is a 64-bit floating-point number, which means it can store a wide range of values, including very small and very large numbers. The "float" part indicates that it can represent fractions, while "64" refers to the number of bits used for storage, allowing for greater precision compared to smaller floating-point types. In many programming languages, such as Python and Java, Float64 is commonly used for calculations that require a high degree of accuracy, such as scientific computations and financial applications. This data type follows the IEEE 754 standard, which ensures consistent behavior across different systems and platforms.