The character list for ICTVdB consists of over 2600 different viral properties which are used to describe and characterise viral taxa. Because of the length of this list, we present it here as a series of separate pages. If your browser can display forms, and is configured to run Java applets, a tree structure should appear in a frame to the left of this one. This tree provides a hierarchical outline of the character list, and may be used to navigate to any portion of the list.