We're continuing our celebration of the 60th anniversary of Doctor Who with the second of our special episodes that asks a simple but important question: "What is an essential element of Doctor Who?"

20 fans answer this question -- some of them from the Reality Bomb archives, most others are new. All of them talk about the diverse elements that makes Doctor Who the amazing program it's been for 60 years. In part two, we have...

• Essential #11: Evolution with Jason A. Miller
• Essential #12: What-if? with Amanda Rae Prescott
• Essential #13: Emotional Entanglements with Petra Mayer
• Essential #14: Ambition with Jim Sangster
• Essential #15: Acting with Scot Clarke
• Essential #16: Ego with Sage Young
• Essential #17: Breadth with Joy Piedmont
• Essential #18: Hope (part two) with Lacy Baugher-Milas
• Essential #19: The Human Condition with Rachel Donner
• Essential #20: Curiousity with KatyBeth Schmid
• Epilogue: The Future with Graeme Burk