| Container and Image Labels | Labels allow you to attach user-defined metadata to containers and images that can be used by your tools. For additional information on using labels, see [Apply custom metadata](http://docs.docker.com/userguide/labels-custom-metadata/#add-labels-to-images-the-label-instruction) in the documentation. |
| Windows Client preview | The Windows Client can be used just like the Mac OS X client is today with a remote host. Our testing infrastructure was scaled out to accommodate Windows Client testing on every PR to the Engine. See the Azure blog for [details on using this new client](http://azure.microsoft.com/blog/2015/04/16/docker-client-for-windows-is-now-available). |
| Logging drivers | The new logging driver follows the exec driver and storage driver concepts already available in Engine today. There is a new option `--log-driver` to `docker run` command. See the `run` reference for a [description on how to use this option](http://docs.docker.com/reference/run/#logging-drivers-log-driver). |
| Image digests | When you pull, build, or run images, you specify them in the form `namespace/repository:tag`, or even just `repository`. In this release, you are now able to pull, run, build and refer to images by a new content addressable identifier called a “digest” with the syntax `namespace/repo@digest`. See the the command line reference for [examples of using the digest](http://docs.docker.com/reference/commandline/cli/#listing-image-digests). |
| Custom cgroups | Containers are made from a combination of namespaces, capabilities, and cgroups. Docker already supports custom namespaces and capabilities. Additionally, in this release we’ve added support for custom cgroups. Using the `--cgroup-parent` flag, you can pass a specific `cgroup` to run a container in. See [the command line reference for more information](http://docs.docker.com/reference/commandline/cli/#create). |
| Ulimits | You can now specify the default `ulimit` settings for all containers when configuring the daemon. For example:`docker -d --default-ulimit nproc=1024:2048` See [Default Ulimits](http://docs.docker.com/reference/commandline/cli/#default-ulimits) in this documentation. |
| Commit and import Dockerfile | You can now make changes to images on the fly without having to re-build the entire image. The feature `commit --change` and `import --change` allows you to apply standard changes to a new image. These are expressed in the Dockerfile syntax and used to modify the image. For details on how to use these, see the [commit](http://docs.docker.com/reference/commandline/cli/#commit) and [import](http://docs.docker.com/reference/commandline/cli/#import). |