There's lots of stuff that we build, and we say things like, "Language X is slow, but it doesn't matter." "Language Y uses a lot of memory, but it doesn't matter." This is very, very often true. But every once in a while, it really matters.

That's when you want something like Rust. When the details are important. When you need full control, but you'd like a compiler to help catch your mistakes. When a garbage collector has too much overhead. When you need to write something inside of Language X or Y, instead of a C extension, you can use Rust.

Basically, anywhere you'd use C or C++, Rust is a great fit. Elsewhere? Maybe, maybe not. Depends.

    Rust is a systems programming language that runs blazingly fast,
    prevents nearly all segfaults, and guarantees thread safety.[1]

It offers low-level access like C or C++ but excels with vastly improved security. So, I'd take that step, and say that where C or C++ is used right now, you might want to use Rust in the future.

[1] http://www.rust-lang.org/