Many of the programs that I write, I write in the Java programming language.

To run Java programs, you will need the Java Runtime Environment (JRE). The JRE is available for free from Sun Microsystems. Also, get the SE edition, not the ME or EE edition. The EE will work, but has extra stuff that's not needed. Do not get the ME edition; it won't work.

Finally, you'll want to get the JRE, not the JDK. The JRE is labeled explicitly as "JRE". It won't be among the first choices for downloading, but it will be near those first options. The JDK won't hurt anything, but it's a lot more stuff than you need.