In C# 1.0 a property's get and set accessors always shared the same access level. If you wanted a publicly readable but privately writable property you had to fall back to a read-only property with a separate private method or field to set the value.

C# 2.0 allows one of the accessors to have a more restrictive access modifier than the property itself.

Code

Now

class Account
{
    public string Name { get; private set; }

    public Account(string name)
    {
        Name = name;
    }
}

Before

class Account
{
    private string name;

    public string Name
    {
        get { return name; }
    }

    public Account(string name)
    {
        this.name = name;
    }
}

Notes

• Only one accessor can have a different access level, and it must be more restrictive than the property itself
• Common combinations are public get / private set and public get / protected set
• This feature is used extensively with Auto-implemented properties ^{C# 3.0}

More information

• C# Language Reference