How to use tokens in a node? I added a new content type. How can I use tokens when editing a node of that content type?

For example, if I put "Hello [user:name]", the page shows the following:



As shown above, the "[user:name]" token in it is not replaced with the username.
You need a text filter to replace tokens in fields. You can configure them in admin/config/content/formats. In drupal 7 you can install the needed text filter with:

Token Filter

But this will not be ported to drupal 8 in the same way as in drupal 7:

Issue Token Filter in Drupal 8

As this is a very simple piece of code, there is an unofficial version for drupal 8:

token_filter-8.x