If you’re on a network that has restrictions or requires authentication before allowing you to use it, you can create a DNS tunnel and surf freely. This tunnel works by funnelling your traffic over port 53 as DNS requests.
You’ll need a dedicated server or a VPS and specialised software. You’ll also need control over a TLD (e.g .com, .net, .co.uk).
If you’re stuck in an office with restrictive browsing, you can use this tunnel to get around the blocks.