How to create a docker image?

`cd` to a directory you like.
Create a file `Dockerfile` or what you like. Say, it is a image about web, you can name it `web.dockerfile`.
A `Dockerfile` is a blueprint about a docker image. Now we need to config it, describing what we want the image to be. To learn more about how to config a `Dockerfile`, you may want to see:

How to config a Dockerfile?
Build the image with the finished `Dockerfile` by these commands:
BASH
```
docker build .
```
If you use the custom file name, like `web.dockerfile`:
BASH
```
docker build -f web.dockerfile .
```
If everything is fine, your image would be created. You may want to use these commands to check it:
BASH
```
docker image ls
```