You use the ref keyword in the following contexts:

• In a method signature and in a method call, to pass an argument to a method by reference. :::code language="csharp" source="./snippets/refKeyword.cs" id="PassByReference":::
• In a method signature, to return a value to the caller by reference. For more information, see ref return. :::code language="csharp" source="./snippets/refKeyword.cs" id="ReturnByReference":::
• In a declaration of a local variable, to declare a reference variable. :::code language="csharp" source="./snippets/refKeyword.cs" id="LocalRef":::
• As the part of a conditional ref expression or a ref assignment operator. :::code language="csharp" source="./snippets/refKeyword.cs" id="ConditionalRef":::
• In a struct declaration, to declare a ref struct. For more information, see the ref structure types article. :::code language="csharp" source="./snippets/refKeyword.cs" id="SnippetRefStruct":::
• In a ref struct definition, to declare a ref field. For more information, see the ref fields section of the ref structure types article. :::code language="csharp" source="./snippets/refKeyword.cs" id="SnippetRefField":::
• In a generic type declaration to specify that a type parameter allows ref struct types. :::code language="csharp" source="./snippets/refKeyword.cs" id="SnippetRefGeneric":::