Rust lifetime errors with structs holding references

Defining a struct that holds a reference requires lifetime annotations. Without them, the compiler throws errors. Adding lifetimes then propagates complexity throughout the codebase.

Prefer owned data (String instead of &str, Vec<T> instead of &[T]) in structs unless performance is critical. If you must use references, add lifetime: struct Foo<'a> { name: &'a str }. Use Cow<'_, str> for flexibility between owned and borrowed. For self-referential structs, use Pin or ouroboros crate. Rule of thumb: if the struct outlives the function that creates it, use owned types.

Rust lifetimes ensure references don't outlive the data they point to. Structs with references must prove at compile time that the data lives long enough.