float64 is a data type used in programming and computer science to represent numbers with decimal points. It is a 64-bit floating-point format, which means it can store a wide range of values, including very large and very small numbers. This format is particularly useful for calculations that require precision, such as scientific computations and financial applications. In programming languages like Python and Go, float64 allows developers to perform arithmetic operations on decimal numbers efficiently. The "float" part indicates that the number can "float" or change its position based on the decimal point, while "64" refers to the number of bits used to store the value, providing a good balance between range and precision.