3.5 Member access
Declarations of members allow control over member access. The accessibility of a member is established by the declared accessibility (Section 3.5.1) of the member combined with the accessibility of the immediately containing type, if any.
When access to a particular member is allowed, the member is said to be accessible. Conversely, when access to a particular member is disallowed, the member is said to be inaccessible. Access to a member is permitted when the textual location in which the access takes place is included in the accessibility domain (Section 3.5.2) of the member.