What does “the session was packed” mean in this context?

Question

I couldn’t believe the hall wasn’t standing room only. But I probably shouldn’t have been surprised! I was at the Cannes Lions International Advertising festival, and in an auditorium next door, Anderson Cooper was having an onstage discussion with Conan O’Brien. That session was packed. Meanwhile, in my forum, a little-known Chinese executive named S.Y. Lau was speaking.

Checking the translation of pack does not show very good relation in this sentence, however I guess they mean session was recorded? Please advise.

Answer 1

"The box is packed" roughly means "the box is full".

Similarly, sometimes we say about events like that, that they are packed, to mean something like "It would be hard to fit more [people] in". So the session was crowded or fully booked up (no space for more guests or spectators).

Answer 2

From the OED, "To Pack" is:

a. transitive. To put (persons or things) together closely or compactly; to form into a compact mass or body; to crowd together. Frequently in passive.

c. intransitive. Of a group of people: to crowd or squeeze into a small vehicle, room, etc.

"With much of the school closed off for cleanup or construction, its 2,800 students are packed into jury-rigged classrooms in gymnasiums, basements and cafeterias."

So "That session was packed" means "That session had a lot people" and will likely be understood as "That session was extremely popular."