The absolute highest quality domains in existence.  They command the highest prices due to their short, common word domains that have a high-demand in the market.  These are names that businesses and investors strive to acquire, but are extremely rare, making up just 0.5% of the domain market.
Still rare, these domains are only 1% of the registered domain names.  They are short domains made of less common words than tier 1, but still have a high market demand.
Uncommon domain names, which make up only 5% of the market, and are very brandable for a success driven startup, small business, or mid/large business buying a domain that matches one of their product names, or for business use.  They are typically under 15 characters in length, usually 2 words or common 3 word phrases, and have a medium to high market demand.
While more common, Premium Names are still hard to find, being in the top 14% of domain names.  These domains work well for startups & small businesses, or mid/large businesses buying a domain that matches one of their product names.