Junctioning allows you to 'Junction' the magic that your character has in his or hers inventory
to produce noticable effects to your character's statistics. For example, if Squall's HP is at 2143 and you then junction
100 Fire spells to his HP statistic through the 'HP J' junction
ability, his HP will increase by 100 to 2243. That example replaces Final Fantasy VII's 'HP Plus' Materia idea.
You can mess around with all sorts of statistics, such as luck and strength, but only when
you have gained the appropiate junction ability first; you can't junction magic to your character's
Strength statistic without having an equipped Guardian Force learnt the 'Strength Juntion' ability.
For more information, go to the Junction Abilities page.
The chart below shows the affects of juntioning 100 spells of
each magic to a character's statistics: