Triad Inversions: How to Play One Chord Across the Whole Neck
A triad inversion is the exact same chord, the exact same harmony (see [[guitar-triads-explained:the article on triads]]), just with a different note on the bottom. The notes stay the same - only their order by pitch changes - and that opens up several different spots on the neck for one chord.
Root position: the root on the bottom
In root position, the lowest note is the chord's root - for a C major chord, that's C on the bottom. This is the most familiar, 'settled' sound of a chord - it's usually what people mean by just saying 'a C chord'.
First inversion: the third on the bottom
If the third ends up on the bottom instead of the root, that's the first inversion. The harmony stays exactly the same (it's still called a C major chord), but the sound is a bit less 'settled', lighter, because the most stable note (the root) is no longer in the bass.
Second inversion: the fifth on the bottom
If the fifth is on the bottom, that's the second inversion, and it sounds even less settled than the first. In practice, the second inversion is used less often than the first exactly because of that more 'suspended' feel, but it remains the same chord in terms of which notes it's built from.
Why this matters on guitar at all
Inversions give several different spots on the neck for the same chord (the same principle as in the article on playing one chord in different places - see the article), but through an actual change of the bottom note, not just sliding the same barre shape. This is especially useful for smooth bass movement between the chords of a progression.
Where to start working through it
Take one familiar major chord, find its three notes (root, third, fifth) within one small area of the neck, and try playing all three versions of the bottom note in a row, listening to how the character of the sound changes while the harmony stays exactly the same.
Try it in practice
Open chord trainer