You swap assets by sending them into pools containing RUNE and other assets.Swaps are calculated at prices relative to the ratio of assets in the pools. You can swap both ways, or swap and send to someone else.When you swap, you change the balances of the assets in the pool, creating a SLIP since it changes the price. The deeper the pool, or the smaller your transaction, the less slip. A small fee proportional to the slip is paid to whoever put assets in the pool. Fees are always fair and transparent.