LINQ คืออะไร?

 adults = people
    .Where(p => p.Age >= )             
    .OrderBy(p => p.Name)                 
    .Select(p => p.Name.ToUpper())        
    .ToList();                            


 total = numbers.Sum();
 count = people.Count(p => p.IsActive);
 first = people.FirstOrDefault(p => p.Id == );   
 any = people.Any(p => p.Age > );
 groups = people.GroupBy(p => p.City);            
 max = people.Max(p => p.Age);