What changes
A VPN creates a tunnel to a VPN server. Internet destinations generally communicate with that server's public address, so IP geolocation describes the VPN endpoint instead of your normal ISP connection.
What does not automatically change
Cookies, logged-in accounts, browser characteristics and other identifiers can remain. Changing the public IP is an important privacy/network effect, but it is not the same as becoming anonymous.
How to verify a VPN
Save your current public IP, enable the VPN, then check again. A different address and network/ASN are strong signs that your web traffic is exiting elsewhere. Also inspect WebRTC and IPv6 behavior because browser/network paths can differ.
Why VPN detection can disagree
VPN providers change infrastructure, use residential or hosting networks, and rotate addresses. Detection services therefore classify based on current intelligence and can produce false positives or false negatives.
Why the ASN matters as much as the address
Seeing a different IP after connecting is useful, but checking the ASN and network organization helps confirm where the new route exits. If the new address belongs to the expected VPN or hosting network, the result is easier to interpret than a bare before-and-after number.
What if the IP does not change?
The VPN may not be connected, the application may be bypassing the tunnel, split tunneling may be enabled, or the check may have occurred before the route changed. Reconnect, refresh the page and compare the network information again.