How to declare a variable in C#?

In C#, declaring a variable is the process of specifying its name and data type to reserve memory space for storing data. Variables are essential for storing and manipulating values in your programs. To declare a variable in C#, you need to follow these basic steps:

1. Choose a Descriptive Name: Start by selecting a meaningful and descriptive name for your variable. This name should reflect the purpose or content of the variable to make your code more readable. Variable names are case-sensitive in C#.

2. Specify the Data Type: Next, you need to specify the data type of the variable. C# is a statically typed language, which means you must declare the data type before using the variable. For example, if you want to declare an integer variable, you use the `int` data type.

3. Use the Assignment Operator: After specifying the data type, you can use the assignment operator (`=`) to assign an initial value to the variable, if desired. For example, `int myNumber = 42;` declares an integer variable named `myNumber` and assigns it the value 42.

4. Optional Initialization: You can also declare a variable without immediately initializing it. In this case, the variable will hold a default value according to its data type. For example, an uninitialized `int` variable will have a default value of 0.

Here’s a simple example of declaring and initializing variables in C#:

```csharp

int age = 30; // Declaring and initializing an integer variable

string name;   // Declaring a string variable without initialization (default value is null)

bool isActive = true; // Declaring and initializing a boolean variable

```

Keep in mind that variable declarations must occur within a method, constructor, or property in C#. The scope and lifetime of a variable depend on where it’s declared. Properly declaring and using variables is fundamental to writing effective and maintainable C# code.