Docker is based on Linux containers and control groups. But I would like to know which implementation of Linux containers , docker is using? Is it using the native/default (LXC execution environment ) of Linux or they have their own implementation of this? 
Which container implementation docker is using
lxc;docker
Docker uses their own libcontainer library after they switched from using LXC in 2014.LXC uses their (www.linuxcontainers.org)  liblxc library.Both libraries utilize the linux kernel namespaces technology.LWN had a multi-part blog on namespaces:  https://lwn.net/Articles/531114/ 