certificate format

What is the difference between PEM and DER certificate extensions?
In most cases it doesn’t matter which format you choose but some key stores may require a specific format/file extension and some business partners may demand that the certificate is sent to them (or uploaded to their system) with a particular format/file extension.

PEM–Format:
*.CER and
*.PEM -> contains the X.509 certificate encoded in text (base64 and encrypted) – both have the same content, the different extensions are provided just for the convenience of the user – some software systems require the CER extension and other require the PEM extension.

DER–Format:
*.CER and
*.DER -> contains the X.509 certificate in binary form - again, the same content, the different extensions are just for the convenience of the user.