In Rust, a tuple is an ordered collection of elements of different types. It is a way to group multiple values together into a single compound value. Tuples in Rust are similar to tuples in other programming languages and provide a convenient way to handle and pass around multiple values as a unit.

Here's how you can declare and use a tuple in Rust :

let my_tuple: (i32, f64, bool) = (10, 3.14, true);​

In the above example, we declare a tuple named `my_tuple` that contains three elements: an `i32`, an `f64`, and a `bool`. The tuple is assigned values `(10, 3.14, true)`.

Tuples can have elements of different types, and their types are determined by the types of their individual elements. In the example above, the types of the elements are explicitly specified as `i32`, `f64`, and `bool`. However, Rust can also infer the types of the elements in some cases, so the type annotation can be omitted.

You can access the elements of a tuple using pattern matching or by using the dot (`.`) operator followed by the index of the element :

let my_tuple = (10, 3.14, true);

// Using pattern matching
let (x, y, z) = my_tuple;
println!("x: {}", x);  // Output: x: 10

// Accessing individual elements
println!("y: {}", my_tuple.1);  // Output: y: 3.14​

Tuples can be used in various ways in Rust :

1. Returning Multiple Values : Functions can return tuples to conveniently return multiple values. This allows you to capture and use multiple results from a function call.

2. Function Parameters : Tuples can be used to pass multiple values to a function as a single argument. This can be useful when you want to pass a group of related values without creating a separate struct or enum.

3. Data Grouping : Tuples can be used to group related data together when there is no need for named fields, such as temporary calculations or intermediate results.

4. Pattern Matching : Tuples can be deconstructed using pattern matching to access individual elements. This allows you to extract and work with specific values from a tuple.

5. Iteration : Tuples can be iterated over using loops or iterator methods, allowing you to process each element sequentially.

Tuples in Rust are fixed-size and have a fixed number of elements. Once a tuple is created, you cannot add or remove elements from it. If you need a collection with a variable number of elements, you can use vectors (`Vec`) or other data structures provided by the Rust standard library.