Core Location: Theory and Mapping
Also included in the Nucleus.
An interval is the relationship between any two tones. Sometimes it is defined as the distance between tones, & that is one dimension to what they are. They are also the sounding relationships, or interactions, between any two tones. We can identify them with our hearing, by how they resonate. We should be able to identify intervals by listening (melodic - one after another, and harmonic - at the same time).
Before looking at the guitar fretboard, let's look at the names for each type of interval. For more naming options, see Tone Naming.
Now let's apply these to the guitar, starting with the intervals between the open strings.
The open strings in standard tuning have these intervals between the strings. If closed, they are the same. And interval types can also be described in half steps.
The black dot is any root [the lower down the string the root is located, the nut cuts off some of the possibilities - this is true for any string].
The interval shapes and relationships from the 5 string are the same as string 6. Makes sense of this...since the intervals between the strings are the same, the shapes are as well.