What is LINQ to SQL?

[Moldraxian]

I've been doing some research and I've been seeing many things about something called LINQ. It looks like a way to build complicated SQL queries but it is very hard to understand. Does anyone have any tips that would help LINQ make more sense?

I made my own query and I had this error pop up:
Cannot perform 'Like' operation on System.DateTime and System.String.

I don't understand why I get this error but this is my code.

Code:

Private Sub txtOrder_TextChanged(sender As System.Object, e As System.EventArgs) Handles txtOrder.TextChanged
        If txtOrder.TextLength > 0 Then
            All_flood_certsBindingSource.Filter = String.Format("[Order Received] Like '" & txtOrder.Text) & "'"
        Else
            All_flood_certsBindingSource.Filter = String.Empty
        End If
    End Sub