Fragrances have three distinctive levels that give the fragrance depth: top notes, middle (heart) notes, and base notes.
Top notes are generally the lightest and what you smell initially.
The middle (heart) notes act as a liaison between the top and base notes giving the fragrance a heart, hence the name.
Base notes are the foundation; They last the longest. Once your candle has been lit for a few hours, the base notes will be the most predominant.