diff --git a/src/lib.rs b/src/lib.rs
index 7c2864e..dc27629 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,3 +1,13 @@
+//! This crate provides low-level types for implementing Zcash specifications. When a
+//! common function defined in [the Zcash Protocol Specification] is used in multiple
+//! protocols (for example the Sapling and Orchard shielded protocols), a corresponding
+//! common type in this crate can be shared between implementations (for example by the
+//! [`sapling-crypto`] and [`orchard`] crates).
+//!
+//! [the Zcash Protocol Specification]: https://zips.z.cash/protocol/protocol.pdf
+//! [`sapling-crypto`]: https://crates.io/crates/sapling-crypto
+//! [`orchard`]: https://crates.io/crates/orchard
+
 #![deny(rustdoc::broken_intra_doc_links)]
 
 mod prf_expand;