Complex sentence: Amy Kaitlin Olson (born August 18,1975) is an American actress best known for playing Deandra "Sweet Dee" Reynolds in the television series "It's Always Sunny in Philadelphia".
Split into simpler sentences: Amy Kaitlin Olson (born August 18,1975), known professionally as Kaitlin Olson, is an American actress. She is best known for playing Deandra "Sweet Dee" Reynolds in the television series "It's Always Sunny in Philadelphia".