Q:

It says outdated server, when I try to join my friends world, got any answers? (V. 1.9)

I try to join my friends server, it says outdated server, got answers? V.1.9

A:

This means that the server is running a different version of Minecraft than you're using to try and join the server with.
If you are joining the server with a client on 1.9:

The server is running a Minecraft version prior to 1.9.

To fix it, you'll need to change the game version:

Open the launcher.
If they are there, click the three white bars in the top right. If there's a white "x", continue to the next step.
Select "Launch options".
Select "+ Add new".
Give it a name (such as the version you are going to use), then from the dropdown menu below the name select the version you want.
Click save.
Select "News" from the menu up top.
Click the green arrow near the bottom of the launcher and select the profile you just created, then click "PLAY".

Since you don't know what version the server is on, either find out from your friend or try different versions until you are able to join - I'd recommend trying 1.8.9 and 1.7.10, as they're the most popular pre-1.9 versions.

If the server is on 1.9:

You are joining with a client that is more updated than the server. You probably are using 1.13.2, the default version when you first use the launcher. 

To fix it, you'll need to change the game version:

Open the launcher.
If they are there, click the three white bars in the top right. If there's a white "x", continue to the next step.
Select "Launch options".
Select "+ Add new".
Give it a name (such as the version you are going to use), then from the dropdown menu below the name select the correct version (1.9, according to what you said).
Click save.
Select "News" from the menu up top.
Click the green arrow near the bottom of the launcher and select the profile you just created, then click "PLAY".

