How do I categorize torrents in Deluge?

Yes you can use the Label plugin to do this.

Enable the plugin by opening Preferences, navigating to the Plugins page and ticking the Label plugin:

Create a label (or modify it options) by right-clicking on the Labels section in the sidebar:

Assign a label to a torrent by right-clicking on the selected torrent(s) and then select your label from the sub-menu:

The Label plugin is included with Deluge but there is also a more powerful third party plugin LabelPlus with the following features:

• Sublabels
• Less restrictive label names
• Ability to rename labels
• Relative move completed paths
• Auto-labeling based on torrent name or tracker

• Limit torrent speed by label

  Download LabelPlus