If you reply to a thread, you’ll automatically start following the topic. This is a default setting (see your settings). Following a topic means you’ll receive a notification when there’s a new reply. In your profile, you’ll find an overview of the topics or subcategories you’re currently following.
Slightly different from ‘following’, you also have the option to bookmark topics. You don’t necessarily need to interact with these topics, but when you come across a topic you want to save for future reference, you can simply bookmark it, making it easy to find when you need it.
If you want to be kept up-to-date, sign up for email notifications. You can choose when you want to receive a notification and how often. It’s the best way to stay on top of latest updates.