Watch the Overview of Triad Positions online guitar lesson by Matthieu Brandt from Guitar Lab: Triads and Hendrixian Double Stops
There are three positions of the major triads on the I chord. All three are movable shapes with the roots on string four, three and two; respectively. One is a root postion chord, because the root is in the bottom.
The second is a first inversion triad, because the bass note is the major third of the triad. The root is on string two.
And the third triad is a second inversion, the perfect fifth of the triad is on the bottom. Root is on string three.
These three positions are the basic areas in which you can find the other major and minor triads to create smooth guitar arrangements and locate possible target notes or solos. In this lesson we'll focus on the first position.