Today I learned interesting things about needs and wants. I.e. that wants are indeed expression of needs, although they are not really that accurate. We even may be unaware of the underlying needs, even though the particular want may point direction (or not).
Next question is indeed, how to identify the needs in self and others with higher accuracy.
First thing to do would be to define a need.
Merriam Webster has several definitions, but the psychological definition would be a physiological or psychological requirement for the well-being of an organism.
To put it more simply: need is the feeling of lacking something (in order to feel happy).
We are always expressing our needs. This helps ourselves to understand our own and the needs of others better.