Application Containers (or OCI containers) are designed to run a single application. They use the same underlying technologies as System containers, but their filesystem is usually much smaller with only the minimal dependencies needed for running the application.
In Linux there are several tools for creating and managing application containers. Docker, Podman and containerd just to name a few. Usually Docker and Podman are the choices for end-users such as developers, while containerd is a lightweight runtime intended to be used by orchestrators such as Kubernetes.