Smartphones, tablets and other gadgets aren’t just changing the way we live and work. They are shaking up Silicon Valley’s balance of power and splitting up businesses. Long-established companies such as Hewlett-Packard Co. and eBay Inc. are scrambling to regain their footing to better compete against mobile-savvy trendsetters like Apple and Google, as well as rising technology stars that have built businesses around “cloud computing.”

That term covers a swath of Internet-driven services that shifted technology from the days software users paid a one-time fee to buy and install programs on individual machines where they also stored all their data on hard drives. But with the advent of the “cloud,” people can now rent software to use over the Internet. This enables customers to access documents, pictures and other vital information from any kind of Internet-connected device, a convenience that’s become a necessity during the past few years as people increasingly rely on smartphones and tablets instead of laptop and desktop computers.