What it measures
Five broad traits, each on a scale rather than as a category: openness, conscientiousness, extraversion, agreeableness, and emotional reactivity.
Why it matters in a relationship
Scales describe the everyday texture of living with someone — how much order they need, how much social contact, how strongly they react when something goes wrong, how readily they accommodate someone else.
How we use it
We look at where your two profiles line up, where they diverge sharply, and where a difference is likely to be complementary rather than a problem.