Do you need to use a SSL certificate?

No, there is no technical requirement that you must use a SSL certificate on your website. By using a SSL certificate results in the connection between your website and your visitors computer being encrypted and secure. If you do not use a SSL certificate than the connection would not be encrypted and not secure. Depending on what kind of material and information that you are transmitting to your visitors. It may be appropriate to use a SSL certificate for parts of your website that transmit sensitive account information.