I am responsible for maintaining two Debian servers. Every time I have to do anything with security certificates, I Google for tutorials and beat away until it finally works. However, in my searches I often come across different file formats (.key, .csr, .pem) but I've never been able to find a good explanation of what each file format's purpose is. I was wondering if the good folks here at Server
![What is a Pem file and how does it differ from other OpenSSL Generated Key File Formats?](https://cdn-ak-scissors.b.st-hatena.com/image/square/1d7824625a3ecbc3a39062b14aaa9db8a44aa022/height=288;version=1;width=512/https%3A%2F%2Fcdn.sstatic.net%2FSites%2Fserverfault%2FImg%2Fapple-touch-icon%402.png%3Fv%3D9b1f48ae296b)