There are a number of resources that help users understand Zcash.

Zcash Global

The official Zcash Global community discord

Zcash Media

Zcash Media is an independent organization that makes educational documentaries about Zcash.

Twitter

Twitter is the de facto communication hub for the Zcash community, and the broader cryptocurrency as well. It's a great place to get a pulse check on all things Zcash, and also follow prominent community members. Here's a document that lists the top accounts to follow.

The Zcash Forum

As mentioned in the new user guide, the Zcash forum is a great place to have long form discussions about Zcash topics and also proposed ideas. Proposals always make it to the forum so the community has a chance to discuss and debate the proposed ideas.

Z.cash

Z.cash is Zcash's main website. It provides content and documentation of Zcash for a wide range of users and allows new users to dive deeper into the technical explanations around Zcash.

Zcash Github

Got coding chops and want to dive deeper into the technical side of Zcash? The Zcash Github Repo is the repository for zcashd, the first Zcash node implementation.

Zcash Foundation Github

Another GitHub repository hosting projects of the Zcash Foundation, including zebra, a Zcash node implementation in Rust.

Halo2

The concepts behind zero-knowledge proof systems.

Zcash RPC Docs