I guess we sort of 'know' what emotions are but find them quite hard to describe because there is so much to them. Maybe it's helpful to see them as 'states' that have body and mind components to them.
Whether we are filled with sadness or joy we experience these as sensations in our physiology or particular mental states. Often there are no thoughts involved or maybe there are rapidly moving thoughts that swim through us like a flowing current that's hard to control. Thoughts that do arise can be often rather 'black and white' with a more limited view of the multiple shades of grey that make up reality. It's hard to 'think' clearly sometimes. We can be overwhelmed, in pleasurable or painful ways.
Advertising works because of this system within us. The advert encourages us to associate some sort of desirable experience with the product. Sensual imagery conditions us to entice us. If we become curious about the adverts we can see how they operate. If we also become curious about our emotions we can begin to see how they get constructed, what the activating agents were and how we pattern matched. The interesting thing is that as soon as we become curious we become a little calmer. Asking 'how am I experiencing...?' can be more informing than asking 'why'.
A Moodscope user.