A URL is the address of a page, image, file, or other resource on the internet — the text you type into your browser’s address bar to go somewhere online. Every page you have ever opened had one, whether you noticed it or not. Learn to read a URL and you can tell where a…

You downloaded a file, tried to open or install it, and instead got a message about a “checksum error” or a “checksum mismatch.” In plain words, your computer checked the file, found that it doesn’t match what it is supposed to look like, and refused to trust it. The good news: this is usually fixable…