You can define these anywhere, but it makes sense to define them at the top along with the Org-mode Export Settings. See example in this file.

• roam_alias is a title alias. Useful when finding files.
• roam_tags is for categorization. Also useful when finding files.
• roam_key is a reference. Shows notes with that reference as a link in the backlinks buffer.

Example with two templates.

(setq org-roam-capture-templates
      '(("d" "default" plain #'org-roam-capture--get-point "%?" :file-name "%<%Y%m%d%H%M%S>-${slug}" :head "#+title: ${title}\n" :unnarrowed t)
        ("t" "test" plain #'org-roam-capture--get-point "%?" :file-name "%<%Y%m%d%H%M%S>-${slug}" :head "#+title: ${title}\n" :unnarrowed t)))

• %^{Input} to ask for “Input” value when initiating the capture.
• %i Active region when capture was called.
• Org-mode template expansion docs

• org-roam-insert

One cool trick is to link to a heading in a note. After the filename add ::*Header Name.

[[file:note.org::*My heading][Note - My Heading]]

• Now uses an ID property.
• A map of IDs to file paths is stored in .org-id-locations file, the location of which is determined by the variable org-id-locations-file

• In the note’s buffer, run (org-id-get-create). This will create a properties drawer with the :ID: property and guuid.
• Then run (org-id-update-id-locations). This can also take a file path argument. See also https://org-roam.discourse.group/t/how-to-auto-generate-org-id-following-org-roam-find-file-immediate/1412
• Finally run org-roam-db-sync