Easy Learn C#

Introduction

This page provides a quick reference guide to common C# terminology. Understanding these terms is essential for reading C# code and documentation.

Basic Language Elements

Term	Meaning	Example
Namespace	Container for classes and other namespaces; organizes code and prevents name conflicts	namespace MyProject { ... }
Class	Blueprint for creating objects; contains data and methods	class Person { ... }
Method	Block of code that performs a specific task	void PrintName() { ... }
Variable	Container for storing data values	int age = 25;
Statement	Complete instruction that performs an action	Console.WriteLine("Hello");
Expression	Code that evaluates to a value	x + 5
Parameter	Variable in a method definition	void Add(int a, int b)
Argument	Value passed to a method parameter	Add(5, 10);

Object-Oriented Terminology

Term	Meaning	Example
Object	Instance of a class	Person person = new Person();
Constructor	Special method called when an object is created	public Person(string name) { ... }
Field	Variable declared in a class	private string _name;
Property	Member that provides access to a field	public string Name { get; set; }
Interface	Contract that defines a set of methods a class must implement	interface IDrawable { void Draw(); }
Inheritance	Mechanism where a class inherits characteristics from another class	class Student : Person { ... }
Override	Providing a new implementation of a method defined in a base class	override void Print() { ... }
Overload	Multiple methods with the same name but different parameters	void Print(int x) { ... } void Print(string s) { ... }

Keywords & Modifiers

Term	Meaning	Example
public	Access modifier that makes a member accessible from anywhere	public void Display() { ... }
private	Access modifier that restricts access to within the containing class	private int _id;
protected	Access modifier that allows access from the class and derived classes	protected void Initialize() { ... }
internal	Access modifier that restricts access to the current assembly	internal class Helper { ... }
static	Modifier that makes a member belong to the type itself, not instances	static void Main() { ... }
readonly	Field that can only be assigned during declaration or in a constructor	readonly int MAX_SIZE = 100;
const	Constant value that cannot be changed	const double PI = 3.14159;
virtual	Method that can be overridden in a derived class	virtual void Process() { ... }
abstract	Class or method that must be implemented by derived classes	abstract void Draw();
sealed	Class that cannot be inherited from	sealed class FinalClass { ... }
async	Method that can perform asynchronous operations	async Task ProcessDataAsync() { ... }
await	Pauses execution until an async operation completes	var result = await GetDataAsync();

Special Types

Term	Meaning	Example
Delegate	Type that represents references to methods	delegate void ProcessData(int x);
Event	Notification sent by an object when something occurs	public event EventHandler DataChanged;
Enum	Type that defines a set of named constants	enum DayOfWeek { Monday, Tuesday, ... }
Struct	Value type that encapsulates data and related behavior	struct Point { public int X; public int Y; }
Record	Type for immutable data with value-based equality (C# 9+)	record Person(string Name, int Age);
Tuple	Type that groups multiple elements into a single value	(string, int) person = ("John", 30);
Nullable	Value type that can also be null	int? nullableInt = null;
Task	Represents an asynchronous operation	Task task = GetValueAsync();
Lambda	Anonymous function expression	x => x * x

Common Shortcuts & Symbols

Symbol	Meaning	Example
{ }	Curly braces: Define code blocks	if (x > 0) { ... }
[ ]	Square brackets: Array indexing	int value = numbers[0];
( )	Parentheses: Method invocation, expression grouping	Calculate(x, y);
;	Semicolon: Statement terminator	int x = 5;
.	Dot: Member access operator	Console.WriteLine();
:	Colon: Inheritance, interface implementation	class Dog : Animal
=>	Arrow: Lambda expression, expression-bodied members	public string Name => _name;
??	Null-coalescing operator	string name = value ?? "Default";
?.	Null-conditional operator	int? length = text?.Length;
$	String interpolation	$"Hello, {name}!"
@	Verbatim string literal	@"C:\folder\file.txt"