They are scent-based associations between a stimuli (scent) and an outcome (positive habit or emotional state). It is grounded in Classical Conditioning but built around a Neuro-Linguistic Programming technique, called 'anchoring'. 

Anchoring is a technique from Neuro-Linguistic Programming (NLP), which studies how thoughts influence behaviour.

NLP explores how the brain interprets signals and uses language to help us view thoughts, emotions, and feelings as controllable rather than passive experiences. Anchoring involves associating a response with a trigger, allowing the response to be re-accessed quickly, helping shift focus and influence behaviour.  

One of the core pillars of NLP is the idea that we can change the way we think, feel and behave by changing our focus.

The olfactory bulb processes scent signals and sends them to the limbic system, which includes the amygdala and hippocampus—areas involved in emotions and memory. Research has found that we recall memories triggered by scent 75% more accurately (meaning also the same psychological and physiological sensations) than those triggered by sight. The orbitofrontal cortex, involved in decision-making and reward processing, also helps interpret scents, further linking our sense of smell to emotional and behavioural responses.