An operation is a season of extra content. Valve sells an operation pass, players complete missions for stars, and stars are spent on rewards from a list that only exists during that operation. The Counter-Strike wiki's operations page lists every operation from Payback in 2013 to Riptide in 2021 and notes that operations since Shattered Web have added exclusive weapon collections, stickers, graffiti, patches and cases.
Operations have run at irregular gaps, sometimes years apart, and each one has its own name and reward list. There has been no CS2 operation so far. Instead, Valve's Armory update of 2 October 2024 added an Armory Pass that earns credits from XP, and those credits are redeemed for new weapon collections, cases, charms and stickers, so some traders treat the Armory as an operation in all but name.
Why do operation items go up in price?
Operation rewards can only be earned while the operation runs. When it ends, the total supply is fixed, and every item that gets opened, applied or used leaves the market. Whether prices then rise depends on how many passes were sold and how popular the items are, so some operation cases climb for years and others stay flat.
Some operation collections have also been reachable through trade-up contracts, which means their skins do not always stay rare in every wear tier. Check whether a skin can be produced by trade-up before assuming its supply is fixed.
Is an operation pass worth buying?
From a trading view, the pass is worth it only if the rewards you can earn sell for more than the pass costs, after fees. That depends on the reward list of each operation and on how much you play. The pass also grants access to content and cosmetics that have no resale value, so the answer depends on whether you play enough to finish the missions.
If you are buying operation items rather than earning them, treat them like any discontinued case or collection: supply is fixed, demand is uncertain, and prices can stay flat for a long time before moving.