What is a Niche?
A product niche pertains to a small or particular segment that a marketer focuses on selling. Niches are established by identifying a target market’s needs and wants that are hardly addressed by current retailers. Niche products are usually unique, very specific, relevant to your target market and highly profitable.
Some examples of niches are organic vs regular snacks, or left-handed vs right-handed golf equipment. For more examples you can refer to this guide: https://www.salehoo.com/blog/the-ultimate-dropshipper-list