Liquidity is how quickly a skin sells near its fair price. High-liquidity skins — popular weapons in common wears — resell fast with tight spreads; illiquid items can sit for weeks and force a discount.
Prices are reference quotes from available sources. Check the final price and fees on the marketplace.
Before buying to flip, check how many active listings exist across marketplaces. Thin listings mean wide spreads and slow exits; deep listings mean you can buy and sell close to fair value.