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Answer: Box<T> stores a value on the heap. Boxes are the straightforward smart pointer written as Box<T>.

Deref

Implement Deref to customize what * does for your type. Deref coercion then turns a reference to a Deref type into a reference to its target type.

A Box<T> is a smart pointer to a heap-allocated value of type T.

Claims

• id: C1 claim: Boxes allow you to store data on the heap rather than the stack. source: S1 evidence: "Boxes allow you to store data on the heap rather than the stack."
• id: C2 claim: Box is a straightforward smart pointer type written Box<T>. source: S1 evidence: "straightforward smart pointer is a box, whose type is written Box<T>."
• id: C3 claim: Implementing Deref customizes the behavior of the dereference operator. source: S2 evidence: "Implementing the Deref trait allows you to customize the behavior of the dereference operator *"
• id: C4 claim: Deref coercion converts a reference to a Deref type into another reference. source: S2 evidence: "Deref coercion converts a reference to a type that implements the Deref trait into a"

• id: C5 claim: Values can be boxed (allocated on the heap) by creating a Box<T>. source: S3 evidence: "Values can be boxed (allocated on the heap) by creating a Box<T>."

Sources

• [S1] Using Box<T> to Point to Data on the Heap. The Rust Project (The Rust Programming Language book). https://doc.rust-lang.org/book/ch15-01-box.html . License: MIT OR Apache-2.0. Accessed 2026-11-09.
• [S2] Treating Smart Pointers Like Regular References with Deref. The Rust Project (The Rust Programming Language book). https://doc.rust-lang.org/book/ch15-02-deref.html . License: MIT OR Apache-2.0. Accessed 2026-11-09.

• [S3] Box, stack and heap - Rust By Example. Rust by Example (rust-lang/rust-by-example). https://doc.rust-lang.org/rust-by-example/std/box.html . License: MIT OR Apache-2.0. Accessed 2026-11-09.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted). Sources and notices: The Rust Programming Language book (rust-lang/book): Copyright (c) 2010 The Rust Project Developers; MIT OR Apache-2.0, used under MIT (https://github.com/rust-lang/book/blob/main/LICENSE-MIT). Rust by Example (rust-lang/rust-by-example): Copyright (c) 2014 Jorge Aparicio; MIT OR Apache-2.0, used under MIT (https://github.com/rust-lang/rust-by-example/blob/master/LICENSE-MIT). Text was condensed and changed from the originals.

@misc{iil_note_tep83j26,
  author = {{iinventedlight}},
  title = {{Box and Deref in Rust}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-09},
  url = {https://iinventedlight.com/library/notes/rust-box-and-deref/},
  note = {Permanent ID iil:note:tep83j26. License: CC-BY-4.0.},
}

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