142 words (approximately 1 min)

Where

Where accepts a Func<string, bool> delegate. For each string passed to the function, it returns a bool value.

targeting a named method

static bool NameLongerThanFour(string name) => name.length > 4;

var query = names.Where(new Func<string, bool>(NameLongerThanFour));

Roslyn can instantiate the delegate for us so we can simplify:

var query = names.Where(NameLongerThanFour);

targeting a lambda expression

var query = names.Where(name => name.Length > 4);

OrderBy & ThenBy

var query = names
    .Where(name => name.Length > 4)
    .OrderBy(name => name.Length) // Create groups of names of the same length;
    .ThenBy(name => name); // Within those groups, sort by name.

In query syntax:

var query = from name in names
    where name.Length > 4
    orderby name.Length, name
    select name; // In query syntax, `select` is always required.

OfType

List<Object> objs = new() 
{
    new Person(),
    new Dog(),
    new House()
};

var query = objs.OfType<Dog>();