He opened the PDF. It was 300 pages of beautifully scanned 1970s gear catalogs. By paying attention to that "46.47 MB" label, Leo knew exactly what kind of data strain to expect on his phone plan and what kind of file to look for in his downloads. The Moral of the Story When you see a specific file size like 46.47 MB : Check the source: Do you trust the site?

Instead of clicking blindly, Leo hovered his mouse over the link. At the bottom of his browser, the URL appeared. It didn't lead to a random, gibberish website; it pointed to a reputable file-hosting service.

Leo paused. In the world of the internet, 46.47 MB is a "middle-child" file size. It’s too large to be a simple text document (which are usually under 1 MB), but too small to be a high-definition movie (usually 1,000 MB or more).

Software or, potentially, a virus.

He clicked "Download." Once the file landed in his folder, he didn't open it immediately. He checked the . It was .pdf . If it had been .exe or .scr , he would have deleted it instantly, as there’s no reason for a "guide" to be an executable program.