A set is a collection of items which can be anything. Whatever operator we need to work on these sets are in short the set operators and the operation is also known as set operation. Basic set operation includes Union, Intersection as well as addition, subtraction, etc.
There are some means to chain commands together. Simple ones like just a ; or more complex ones like logical chains which run depending on some conditions. The third one is piping commands, which effectively hands over the output data to the next command in the chain.
Floating-point numbers are numbers that have fractional parts (usually expressed with a decimal point). In Java, there is two primitive types for floating-point numbers which are
float (uses 4 bytes), and
double (uses 8 bytes). This documentation page is for detailing with examples operations that can be done on floating points in Java.