Talk pages
Starting a conversation
User talk pages
Messages for you
Drawing attention
Fetching others to help
Summary
Review what you've learned
Everyone contributing to Wikipedia has their own user talk page. On this page, anyone can leave a message for you. People can ask you questions or give you advice. There are also some automated "bots" that can add helpful messages.
Unregistered users on a shared internet connection, like school or home networks, get a shared talk page. If someone leaves you a message, you'll see a notification at the top of whichever page you're looking at: When you receive a message, you'll get a notification at the top of your screen:.png)
You can reply the same way you would at an article talk page: click the [reply] link after their comment and mention them with the 
icon to notify them.
Generally, you can find an editor's user talk page by following the link labelled "talk" in their signature, located at the end of their messages. You can always reach their user talk page by clicking on their name in the signature, and then clicking on the "Talk" tab, as you would with an article. You can also reach another editor's talk page by typing "User talk:" and the name of the user in the search bar.