What can I buy to get WiFi anywhere?

I'm curious, what kind of device or service would allow me to access WiFi from anywhere I go? Is there a specific type of router or portable hotspot that I could purchase that would enable me to stay connected to the internet no matter where I am? Or are there any subscription-based services that I could sign up for that would provide me with unlimited access to WiFi networks while I'm on the go? I'm looking for a solution that's both convenient and reliable, so I'd appreciate any recommendations you might have.