What is Lightning

Salesforce Lightning is a platform which consists of the Lightning Aura Framework which is used to create single page responsive applications in salesforce. It consists of the following :

Lightning Experience is a single page user interface which is responsive and designed to improve productivity and speed.

Lightning Components standard and custom provide a flexible way to implement functionality in the lightning experience, communities and the salesforce mobile app (Salesforce1). These are of two types : aura and web components.

Lightning App Builder provides a way to create pages via point and click for admins. These pages are used as containers for our lightning aura/web components.

Experience Builder provides a way to develop communities with point and click using standard lightning aura/web components and templates.

Lightning Framework provides a way to develop custom standalone aura/web components which can be used in the lightning experience and the salesforce mobile app (Salesforce1).

Salesforce Lightning Design System (SLDS) provides a css library and best practices to implement the best user interface (UX) for the lightning experience.