Flash channels provide a way to transact for free in high frequency without computing PoW constantly. This reduces the transaction overhead to a negligible level by creating transactions off network. The resulting channels free up users to transact securely with instantly.
Below are some articles about IOTA that have content protected by a microtransaction paywall. SatoshiPay pioneered this system using Bitcoin, but now they can get instant and feeless transactions using IOTA.