How do I access wifi hotspots via laptop when travelling in USA - via passwords or a key from site to site?

I am travelling in the USA and want to access wifi hotspots frommy laptop in various towns and cities.

Are wifi hotspots available/widespread outsie major centres.

How do I access wifi hotspots? For example, do I need to get a password or some sort of access key at each hotspot to access the wifi service, or is there another way of doing it?

Thanks

Greg

Usually public places have a wifi spot. Starbucks, Panera bread and some restaurants or libraries have wifi spots, which they will say it on their doors.

If such places do give free wifi, then there is no password needed.