Finder is a program that allows you to view the files on your mac hard drive, or any other drive that is either connected physically, like a usb device, or through a network. Viewing hidden files is not enabled by default, but you can use a program called Terminal, located in Applications/Utilities/ Type this:

defaults write AppleShowAllFiles true
killall Finder

To hide them, do the same thing, except change true to false. You can also click here, to download what is called a zip file. The file will decompress into a folder. Since that folder, only contains one item, it is what is shown, and since that is a .dmg file, which means disk image, it automatically opens and mounts a drive on your computer. Inside that drive is two files, one that says show all files, and one that says hide all files. Well, their names are self explanatory of what they do. You might have to allow it to run though.

Another thing that finder can do, is connect to any device or even wirelessly connect to a shared computer. It can also connect to an ftp server. An ftp server is a way to transfer files. For example,, will take you to all the files hosted on apples website. However, even though you clicked it in safari, if you look at the top left corner, it says finder. That is because, once it connects, you will see the files in the Finder window.