Jquery doubt

hi,
i am working on jquery i am not understood why are we using ready made functions like jquery.js, jquery.min.js,jquery-1.6.2.min.js,jquery-latest.js.
what is the use of these…
at what situation we are using the particular function…
what are the difference between these functions…

The jQuery library (basically a file of JavaScript code) can be called anything you like. Sometimes the version number is included in the name for your reference (e.g. 1.6.2). To minimize the file size, whitespace can be trimmed out, and in that case the file is often names with a “min” in it to remind you of that.

But in all likelihood, each of those files you listed above is the same thing—the jQeury library—but perhaps some minified and others not, or various different versions of it. (It could be handy to know the version, in case you’ve heard that a slider or gallery script you are using doesn’t work with the latest version of jQuery, for example.)