If two nodes don't share a direct channel, or don't have the required liquidity, the network will automatically find an alternative path through other connected channels that will still reach the target receiver via intermediary nodes within the Lightning Network. Each node along the path forwards the payment using available liquidity, until it reaches its destination.
As long as there is a viable route with enough liquidity across the connected channels, routing allows participants on the Lightning Network to send and receive payments with any other participant. Lightning Wallets (or nodes) automatically analyze and select the most efficient and reliable route based on liquidity, costs, and network conditions.
This process happens securely and privately, as nodes only see the parts of the route they are involved in, not the full path or the identities of the sender and receiver. It's also instant, taking milliseconds to seconds, so it does not affect the transaction's instantaneity.