Top note creates the first influence and impression, so initial spark really important for an impact. The top note molecules evaporate fast, as they are made of lighter ones. Usually, they are of citrus, spicy, green and aromatic/herbal notes.
The middle note is the transition note between top and base note. Once the top note starts faded, the middle shows presence. These notes are usually floral, fruity, spicy, green, aromatic/herbal notes and they are long lasting more than top notes. These notes are more dominant and the core of the fragrance.
Base notes are what remain after middle notes faded away. This is the note creates a memory and leaves footprint in your mind. Powerful longest-lasting base notes also help to boost the staying power of middle and top notes. These notes evaporate very slowly and stay longer period. Usually referred notes are amber, woody, leather, musky leathery and sweet.