1) Balustrade: 
The stair and landing guard rail containing the balusters and handrail.
2) Balusters or uprights: 
Vertical posts that make up the stair or landing balustrade and support the handrails.
3) Handrail: 
This part of the stair guides your hand when using the staircase.
4) Rise: 
The vertical distance from one tread to the next. This needs to be consistent for compliance.
         
         
           5) Newel post: 
The structural post that fits at the top and bottom of the staircase providing stability to the balustrade.
6) Tread: 
The horizontal part of the stair that people walk on.
7) Spacer ring: 
Used as an insert between the treads to ensure a consistent rise.
8) Core pole: 
The centre column of a spiral staircase that the treads are fitted to.