How to connect my iPad to Internet while traveling without wifi

Most hotels offer WiFi service.

if you are elsewhere you could consider getting a MiFi device which can create a WiFi hotspot for your iPad while using cellular data.

See here: http://en.wikipedia.org/wiki/MiFi

Some areas have free "hot spots" but you need to take into account it might make you vulnerable to hacking.

Purchase an iPhone with a data plan, turn on bluetooth on both devices, connect the iPad to the iPhone using bluetooth. You now get your data through your cell phone data plan.