Reading an example tells you what a response looks like. Running it lets you see what happens with your own request.
The IP docs have a Run button next to the response. For this request, the API looks up the address you're connecting from:
GET /ip
Press Run and the sample is replaced with the live response. The page shows the time measured in your browser. The User-Agent example works the same way, using the browser you're reading the docs in.
When you're signed in, the curl examples also fill in your key, so you can copy the request without replacing YOUR_API_KEY first. The browser demo uses ParseAPI's demo key when a key is needed. Requests you run with your own key use your team's access and allowances.
The Run button supports basic lookups. Metered checks and Phone and Time ?deep=true examples stay static, ready to copy and run with your own key. Those profiles are included on paid plans, and existing accounts retain their current Deep access.