Definition
Split tunneling is the configuration of a VPN to route some traffic through the encrypted tunnel and some directly. Implementation varies. Application-based split tunneling lets you choose specific apps to route through the VPN (or to exclude). Destination-based split tunneling routes traffic to specific IPs or domains differently. Inverse split tunneling is the same idea inverted: by default everything goes through the VPN, but listed apps or destinations bypass it.
Why It Is Useful
Common use cases. Streaming a foreign country's content through the VPN while keeping your local banking app on its native IP (which the bank requires). Joining a corporate VPN for work apps while keeping personal browsing direct. Routing only a torrent client through a paid VPN while everything else uses the regular connection. Accessing local network resources (printer, NAS, smart home hub) that would otherwise be unreachable while the VPN is active.
Privacy Considerations
Split tunneling is a deliberate weakening of the VPN's coverage. Anything outside the tunnel is exposed to the local network and ISP exactly as it would be without a VPN. For users with a clear threat model — 'I need privacy for X but not for Y' — this is the right tool. For users who want comprehensive protection, full tunneling without exceptions is safer because it eliminates the chance of accidentally routing the wrong traffic.