In addition to the free developer editions, there are different paid editions that Salesforce offers. The four common types of edition are as follows:
Professional: The professional edition provides limited customization and enhancement opportunities. It is used as a basic CRM with no facility to extend it beyond what is provided out of the box.
Enterprise: This is the most commonly used edition. It provides the ability to extend Salesforce CRM with code.
Unlimited: This is the advanced version of the Enterprise edition is mostly used by large organizations, which require a lot of data space. It provides unlimited customizations.