A sandbox is basically a replication of your Salesforce org you can use for development, testing, and training without disrupting your production environment. Sandboxes are completely isolated from your Salesforce production organization, so anything you do in your sandboxes will not affect your Salesforce production application, and vice-versa. Sandbox provides a set of tools that deliver real, tangible business benefits and it’s not just for developers.
If you make a mess of things, your “real” data and org is protected and your sandbox can be refreshed 29 days from its creation or from the last refresh. You can be created a sandbox in production environment;
Setup > Administration Setup > Data Management > Sandbox
There are three types of sandboxes available to Salesforce.com customers.
Configuration-only sandboxes copy all your production organization’s reports, dashboards, price books, products, apps, and customizations, but exclude all your organization’s standard and custom object records, documents, and attachments.
Developer sandboxes are special configuration-only sandboxes intended for coding and testing by a single developer. They provide an environment in which changes under active development can be isolated until they are ready to be shared. Just like configuration-only sandboxes, developer sandboxes copy all application and configuration information to the sandbox.
Full sandboxes copy your entire production organization and all its data, including standard and custom object records, documents, and attachments.