When you start a new drawing, you probably want it to contain a bunch of things to help you get started -- layers, text/dimension/table styles, maybe even a title block or border.
Now, it's easy enough to put things like these in a regular drawing file, which you could open up and re-save every time you needed a new drawing. But this method has one big draw-back -- having to re-save! I can't think how many times I've opened a file, meaning to use "Save As" to create a new file, only to get wrapped up in making changes before I do it. Next thing I know, I've hit Ctrl+S (force of habit!) and now I've overwritten my original file. Oops.
Fortunately, there's an easy way around this. Go ahead and create a drawing with all your building blocks in it, but when you save it, save it as a Drawing Template, with a DWT extension. Next, point the Template Settings path in the Options dialog, Files tab, to the folder where you saved the DWT.
Now, when you start a new drawing, the New File dialog will open in that folder, enabling you to select your template as your starting point. Best of all, it opens as Drawing1 (or whatever number is next in sequence), making it virtually impossible to accidentally save over your template. Of course you can re-save it manually, by changing the file type again, but Ctrl+S won't surprise you.
In your office, you might be able to just have one template, or you may need several, depending on how many sets of CAD standards you have to follow. Either way, it's an easy way to keep your settings straight.