*Because of a hard-coded limit on computation per block, the ethereum blockchain currently supports roughly 15 transactions per second compared to, say, the 45,000 processed by Visa.
There are a few ethereum scaling projects in the works, each of which tackles a different scalability problem.
The goal of sharding is to move away from requiring 'full' nodes - those which store the full state of the network and every transaction that occurs.
Lightning-style 'off-chain' transactions could bring the technology's capabilities closer to how users were told it was 'supposed to be' - fast and nearly limitless in supply, while still not requiring users to trust any intermediary