Let's say that you took the time to open your favorite program to write a letter or put some information into a spreadsheet. You have been typing for awhile and you want to save it. So you go to File and pick...... now is where things get interesting. You can click Save and it will ask you for a location and name for your file. Or you can hit Save As and still pick a location and name for your file. The difference between now and later is that you have not named the file you just started typing.
Now let's say that a day or so or just an hour later you open the same file and make some changes. A name here a word there, change an address. Now what do you do? You don't hit Save As, unless you want to change the name of the file and possibly try to save over the original file name. All you want to do now is go to File and pick Save. It will put all the changes you just did in the file you are working on.
Now here is one last thing. You open a file you have been working on. You want to make some major changes, but you don't want to lose what you started with. So before you make any changes you open the file, then immediately choose Save As and change the name of the file name. Then you start making your major changes. The program has effectively closed the original file and created this new one for you to work with. All the information in the original file and what ever changes you have made up to this point are saved. The new file name is what you are working with and you now have two files, the original and this new one that you are working with.
Feel free to experiment with some files that you make up and see what happens. Enjoy. If any other questions let me know and I can put the answer here.
