“They were reality TV before it existed.”

That’s how Matt Singer, author of the upcoming book “Opposable Thumbs: How Siskel & Ebert Changed Movies Forever,” describes the two most famous film critics in history. Like countless fans of his generation, Singer – whose book will be published by Penguin Random House on Oct. 24 – credits Siskel and Ebert with stoking his love of cinema at a young age. “They were hugely important to me as a kid,” he says. “I remember thinking they must have the greatest job in the history of the universe.”

Following in his heroes’ footsteps, Singer worked on two different versions of “At the Movies,” which was the second of Siskel and Ebert’s three TV series. He was a guest contributor on the version hosted by Ben Mankiewicz and Ben Lyons, and he worked on “Ebert Presents: At the Movies,” which ran on PBS for one season. Today, Singer is the editor and film critic at ScreenCrush. “Obviously, I wouldn’t do what I do now if not for their show,” he says.

Siskel and Ebert co-hosted more than a thousand TV episodes between 1975 and 1999, and many are available to revisit on YouTube. Looked at today, they offer a fascinating glimpse at the evolution of film criticism, and provide a real-time history of the trends that impacted Hollywood in the ’80s and ’90s. Here is Variety’s guide to the 10 essential Siskel and Ebert episodes, with commentary from Singer.