This method returns an IEnumerable with all the elements that meets the lambda expression

Example

var personNames = new[] 
{
    "Foo", "Bar", "Fizz", "Buzz"
};

var namesStartingWithF = personNames.Where(p => p.StartsWith("F"));
Console.WriteLine(string.Join(",", namesStartingWithF));

Output:

Foo,Fizz

View Demo