The following terms describe different ways to case identifiers.

Pascal Casing

The first letter in the identifier and the first letter of each subsequent concatenated word are capitalized. You can use Pascal case for identifiers of three or more characters. For example: BackColor

Camel Casing

The first letter of an identifier is lowercase and the first letter of each subsequent concatenated word is capitalized. For example: backColor

Uppercase

All letters in the identifier are capitalized. For example: IO

Rules

When an identifier consists of multiple words, do not use separators, such as underscores ("_") or hyphens ("-"), between words. Instead, use casing to indicate the beginning of each word.

The following table summarizes the capitalization rules for identifiers and provides examples for the different types of identifiers:

More information can be found on MSDN.

Interfaces should be named with nouns or noun phrases, or adjectives that describe behaviour. For example IComponent uses a descriptive noun, ICustomAttributeProvider uses a noun phrase and IPersistable uses an adjective.

Interface names should be prefixed with the letter I, to indicate that the type is an interface, and Pascal case should be used.

Below are correctly named interfaces:

public interface IServiceProvider
public interface IFormatable

There are two common conventions for private fields: camelCase and _camelCaseWithLeadingUnderscore.

Camel case

public class Rational
{
    private readonly int numerator;
    private readonly int denominator;

    public Rational(int numerator, int denominator)
    {
        // "this" keyword is required to refer to the class-scope field
        this.numerator = numerator;
        this.denominator = denominator;
    }
}

Camel case with underscore

public class Rational
{
    private readonly int _numerator;
    private readonly int _denominator;

    public Rational(int numerator, int denominator)
    {
        // Names are unique, so "this" keyword is not required
        _numerator = numerator;
        _denominator = denominator;
    }
}

The general format for namespaces is:

<Company>.(<Product>|<Technology>)[.<Feature>][.<Subnamespace>].

Examples include:

Fabrikam.Math
Litware.Security

Prefixing namespace names with a company name prevents namespaces from different companies from having the same name.

Use a singular name for most Enums

public enum Volume
{
   Low,
   Medium,
   High
}

Use a plural name for Enum types that are bit fields

[Flags]
public enum MyColors
{
    Yellow = 1,
    Green = 2,
    Red = 4,
    Blue = 8
}

Note: Always add the FlagsAttribute to a bit field Enum type.

Do not add 'enum' as a suffix

public enum VolumeEnum // Incorrect

Do not use the enum name in each entry

public enum Color
{
    ColorBlue, // Remove Color, unnecessary
    ColorGreen,
}

Add 'exception' as a suffix

Custom exception names should be suffixed with "-Exception".

Below are correctly named exceptions:

public class MyCustomException : Exception
public class FooException : Exception