Scrum is a Product Development Framework. Scrum is one of the frameworks under the Agile umbrella. Using the Scrum framework, products are developed incrementally and iteratively.
The scrum framework is invented by Ken Schwaber and Jeff Sutherland in the mid-90s. They have defined the Scrum framework in the Scrum guide at scrumguides.org.
The Scrum framework is based on empiricism (i.e. knowledge is based on experience) and Inspection, Adaptation & Transparency are the three pillars of the Scrum framework.
The Scrum framework provides the operating boundary for the product development process and defines Rules, Roles, Events, and Artifacts in this process.
The rules of the frameworks are about the roles, events, and artifacts.
The roles in the Scrum framework are – the Scrum team which is made up of the development team, product owner, and scrum master.
The events in the Scrum framework are – the sprint, the sprint planning meeting, the sprint review meeting, the retrospective meeting, and the daily (scrum) standup meeting.
The artifacts are – the product backlog, the sprint backlog, and the product increment.