Day 001 - Downloading jQuery
If you go to http://jquery.com you'll see two versions of the file to download 'production' and 'development'. So what's the difference and which should you use?
This version is used when you come to a point where you're happy with your code and you want push it live. You can upload or deploy your code and then people will be able to access it. In this environment it's useful to use Google's CDN (more on this in Day 002). The end goal here is to serve this file and the content to the user accessing it as quick as possible. The production file is 'minified', it takes the code from the development version and reduces it to use the least amount of characters possible. This makes it difficult when looking at the code to work out what everything's doing, but dramatically lowers the file size.
When building web sites / web apps (What's the difference between a web site and a web application) I'd recommend working locally, this allows you to test your code and make sure everything is working before showing it to the world. Whilst working this way it's often useful, especially whilst learning jQuery to view the development file. It's full of useful comments and generally any method can be found in the jQuery development version source by searching for it then adding
:. There are a few exceptions I believe, but not many.