Although there are many variations and twists, basically real estate markets fall into three categories:

1. Sellers Market

Conversely, in seller's markets, there are more buyers than available inventory. Because there are fewer homes for buyers to choose among, almost every home will sell. Typically, there is much less than six months of inventory in a seller's market. In extreme seller's markets, there is less than two months of inventory in reserve.

2. Buyers Market

Buyer's markets exist when there is more inventory, meaning houses for sale, than buyers. Because buyers have many homes to choose from, not every home for sale will sell. Most experts agree that if six months or more of inventory is on the market, it is a buyer's market. Also note that in buyer's markets, fewer numbers of buyers will result in fewer sales, which can skew median prices.

3. Neutral Market

Neutral markets are balanced. Typically, interest rates are affordable and the number of buyers and sellers in the marketplace are equalized. The scales don't tip in either direction, meaning the market is normal without experiencing volatile swings. Inventory is generally around four months, give or take.
Note that good buys exist in neutral markets, but there are no overall indications that favour buyers over sellers or vice versa.