# `String` vs `str`

We can now understand the two string types in Rust:

```rust,editable
fn main() {
    let s1: &str = "Hello";
    println!("s1: {s1}");

    let mut s2: String = String::from("Hello ");
    println!("s2: {s2}");
    s2.push_str(s1);
    println!("s2: {s2}");
}
```

Rust terminology:

* `&str` an immutable reference to a string slice.
* `String` a mutable string buffer