In a public cloud network, a service provider makes resources, such as applications and storage, available to the general public over the Internet. Anyone who has a Facebook page, a Google Gmail account or any one of hundreds of other Internet services, uses the public cloud.

For bushiness, public cloud services may be free or offered on a pay-per-usage model. Benefits of public cloud networks include easy and inexpensive setup, scalability, and no wasted resources because you pay for only what you use. Prime examples include Amazon AWS, Google Apps, Salesforce.com, Microsoft BPOS, and Microsoft Office 365.

Drawbacks include data security and privacy. You may not know where your data is stored, if or how it is backed up, and whether unauthorized users can get to it. Reliability has become another issue for public cloud networks. A recent two-day Amazon Cloud outage, for example, left dozens of major ecommerce websites disabled or completely unavailable.