The principal line of the hexagram on which the central theme for divination focuses. In most (but not all) cases, the host resides in the second or fifth place (central places within their trigrams), of which the fifth place is most common.  Some hexagrams have more than one hosts. adobe mission uses Master Alfred Huang's The Complete I Ching as its reference guide for hexagram hosts.  The hexagram icons below with line detail show the Host line in BOLD outline.

When a hexagram is written in reverse order (Line 6 becomes Line 1, Line 5 becomes Line 2, etc), an Inverse Hexagram is created.

A hexagram's opposite is the hexagram where each Yin line is Yang and vice versa.  For example, hexagram 1 (The Creative, all Yang lines) and hexagram 2 (The Receptive, all Yin lines) are opposites.

A mutual hexagram is formed by the "mutual" trigrams formed by Lines 2/3/4 and Lines 3/4/5.