In modern browsers that support HTML5, the following is possible:
<a href="https://stackoverflow.com/questions/2793751/link/to/your/download/file" download>Download link</a>
You also can use this:
<a href="https://stackoverflow.com/questions/2793751/link/to/your/download/file" download="filename">Download link</a>
This will allow you to change the name of the file actually being downloaded.