Salesforce Lightning is the latest update in complete Salesforce user interface environment. The new design extends the Salesforce ambient user experience from mobile devices to desktop and Visualforce pages.
The catch is that you have to make your Salesforce instance lightning-ready to fully utilize the UI/UX. You would have to do lots of customization, workflows, reports and dashboards, apps, and Visualforce pages.
The power of Lightning comes with full suite of tools for admin, business users and developers for building apps which automates the complex business processes into faster and easier way.