什么是docker run -it标志？

我正在使用docker做一些复杂的事情，但事实证明，我不知道 -it 标志的含义。
最近我遇到了 docker run 命令的一些示例，这使我有些困惑。

I was doing some complex stuff with docker, but as turn out I don't know what -it flag means. Recently I've come across on some example of docker run command which has confused me a little.

docker run -itd ubuntu:xenial /bin/bash 

我的问题是什么意思如果容器在实例化期间运行 bin / bash

My question is what is sense to write -it flag here, if container during instantiation run bin/bash

-it 标志>在文档中我们有一个例子

In documentation we have an example

docker run --name test -it debian

有解释

-它指示Docker分配一个伪TTY连接到
容器的标准输入在
容器中创建一个交互式bash shell。

The -it instructs Docker to allocate a pseudo-TTY connected to the container’s stdin; creating an interactive bash shell in the container.

并在帮助页面上提供-t标志的说明

and explanation for -t flag from help page

-t，--tty分配一个伪TTY

-t, --tty Allocate a pseudo-TTY

如果在删除过程中删除-it标志

if I delete -it flag during

docker run -d ubuntu:xenial /bin/bash

我新创建的容器没有那么多

my newly created container doesn't live so much

在 docker ps -a

被指定为已退出

抱歉，如果我的问题很愚蠢，我在Internet上找不到解释（对此我有很大的误解）。

Sorry, if my question quite stupid, I can't find explanation on the Internet (I have significant misunderstanding of that point).