Java Development Kit is the official development kit for the Java programming language, especially developed for 64-bit machines.
Programming in any computer language requires a text editor and knowledge of syntax, as well as a clear idea of what is you're trying to create. You then need a compiler to run as an interpreter to translate your code into something understandable. Java is one of the most popular coding languages out there, and Java Development Kit (or JDK) is its official development package.
In addition to the Java Virtual Machine that is essential to perform certain Java-based program types, Java Development Kit has a wide range of tools such as javac, the Java bytecode compiler, javap, disassembler class, and jdb, which is a debugger. You'll find them in Java Development Kit's subdirectory bin. Note though that it doesn't include a graphical IDE (like Eclipse), which requires separate installation.
Unfortunately, if you have very little or no previous experience coding in Java, Java Development Kit is incredibly complicated to learn without aid. Coding novices might find this kit a bit over their heads, although there are some demos and example codes provided within the kit itself.
If you're a seasoned Java programmer, Java Development Kit is an absolutely essential coding tool.