When I'm gonna install packages or software I can see **client | server** versions. What does it mean actually? For example:

```
apt-get install xxxx-client
apt-get install xxxx-server

```

**What are the difference between these?** How can we categorize when we need to install an application or package? Let's say:

If I want to install nginx,
I simply install by typing `apt-get install nginx`,
so there we don't have any confusion.

When I’m looking for MySQL, how to choose which edition should I install? I'm so confused with client and server.