Access modifiers decide who can see and use parts of your code.
public
Anyone can access.
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public class Car
{
public string Model; // Anyone can read/write Model
}
private
Only the class itself can access.
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class BankAccount
{
private decimal balance; // Only code inside BankAccount can see this
}
protected
The class and its children can access.
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class Animal
{
protected void Sleep() { /* ... */ }
}
class Cat : Animal
{
public void Nap() { Sleep(); }
}
The internal Access Modifier
In addition to public, private, and protected, C# provides the internal access modifier.
What is internal?
internalmembers are accessible only within the same assembly (project).- They are not accessible from another assembly, even if referenced.
- Commonly used for code that should be visible throughout a project, but hidden from external code or consumers (such as library users).
Example
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internal class InternalClass
{
internal void DoSomething()
{
Console.WriteLine("This is only accessible within the same assembly.");
}
}
You can also combine protected and internal:
protected internal— accessible from the same assembly or from derived classes.private protected— accessible only from derived classes within the same assembly.
Access Modifier Summary Table
| Modifier | Accessible Within Class | Derived Class (Same Assembly) | Derived Class (Other Assembly) | Same Assembly | Other Assembly |
|---|---|---|---|---|---|
private |
✔️ | ||||
protected |
✔️ | ✔️ | ✔️ | ||
internal |
✔️ | ✔️ | ✔️ | ||
public |
✔️ | ✔️ | ✔️ | ✔️ | ✔️ |
protected internal |
✔️ | ✔️ | ✔️ | ✔️ | |
private protected |
✔️ | ✔️ | ✔️ |
📝 Summary Table
| Modifier | Who Can Access? |
|---|---|
| public | Anyone |
| private | Only this class |
| protected | This class + subclasses |
Tip: Use the smallest possible access for safety.
Next: Working with generics in C#!
