ISPs mushroomed overnight and many have since faded away. Nowadays there is a tendency to choose an ISP which has a well-established record in communications and which has been around for a while. Increasingly the phone companies are providing such services and the cable companies are catching up fast. Neither of these two types of companies are likely to fold up their tents and steal away. International companies such as IBM and Microsoft have established networks that provide connections from anywhere in the world.
Many companies have different packages.
The most convenient is unlimited access to the Net. Other plans are cheaper, but will only give you 10 or 20 free hours a month. The bills can mount up in an alarming fashion with this type of service. There is often a one time charge for hooking you up to the Internet. There may be charges for equipment that you have to have.