As mentioned earlier, floating-point numbers represent what are called “real” numbers, i.e., those that have a fractional part. awk uses double precision floating-point numbers to represent all numeric values. This section describes some of the issues involved in using floating-point numbers.
There is a very nice paper on floating-point arithmetic by David Goldberg, “What Every Computer Scientist Should Know About Floating-point Arithmetic,” ACM Computing Surveys 23, 1 (1991-03), 5-48. This is worth reading if you are interested in the details, but it does require a background in computer science.