Partial implementation of Scrum is not going to make your team Agile or enhance your team’s ability to deliver value earlier. 

Scrum works best when implemented in its entirety. The core of that success is to follow the principles as laid out in the Scrum Guide, which is that each team should have Three (3) roles, Five (5) events/meetings and Three (3) artifacts.

Scrum Roles

1- Scrum Master
2- Product Owner
3- Developer

Events

1- The Sprint
2- Sprint Planning
3- Daily Scrum
4- Sprint Review
5- Sprint Retrospective

Artifacts

1- Product Backlog
2- Sprint Backlog
3- The Product Increment

Some of you might be looking at the events and thinking it is missing the Product Backlog Refinement (formerly known as Backlog Grooming Meeting).  

The Scrum Guide States “Product Backlog refinement is the act of breaking down and further defining Product Backlog items into smaller more precise items. This is an ongoing activity to add details, such as a description, order, and size. Attributes often vary with the domain of work”

Since the Product Backlog Refinement is considered as an ongoing activity and not a specific event. The guideline provided by the Scrum Guide is that a team can take up to (not more than) 10% of their sprint time to do Product Backlog Refinement. Since the environment we are working in is continuously changing and evolving therefore the   refinement of the Product Backlog needs to be an ongoing activity and not an event within the Sprint. 

So, 3-5-3 is the basis of Scrum Roles-Events and Artifacts!!