Twenty-five years ago this week, a then-obscure British physicist in Switzerland wanted to help his employer solve a problem: Given high employee turnover, how can important information and research be retained and shared?

The solution that Tim Berners-Lee came up with, a distributed network of computers and documents linked together by "hypertext," is what we now know as the Web.

It's safe to say no one at the time realized how important Berners-Lee's insight was. Even in 1995, six years after the Web was born, 42 percent of U.S. adults had never heard of the Internet, and 21 percent knew vaguely it had something to do with computers, according to a study by the Pew Research Center.

Most people didn't get what the Web could do until the creation of the browser, a program that presented an easy-to-use interface to help people navigate the Web.

Then, entire industries were born and destroyed, great wealth was created and lost, and people around the world got used to connecting over vast distances.

We're generally forward-looking here in Silicon Valley -- no time for nostalgia.

But we stop to celebrate the many tech milestones. And they are more than a sentimental trip down computer history lane. The anniversaries remind us how much has changed and how quickly. The 10th birthday of Facebook, the 20th year of blogging, and the 30th anniversary of the Mac. And, this year, it's been 45 years since the first connection of Arpanet, the Internet's ancestor. (The Web is often referred to synonymously as the Internet. The Internet is actually the network connecting computers globally. The Web is built on top of it, a way to access and share information (think Web pages) over the Internet.)

Tech anniversaries are also a reminder to take note of how our own expectations have changed.

"We fail to remember that there was a time when a lot of us said, 'Why would anybody ever want to watch a video on a mobile phone?' " said Mike McGuire, a vice president of research at Gartner. "We also fail to remember how we used to settle for watching TV only when a network programmer said we could."

This year also marks the 100th anniversary of the start of World War I, and the 25th anniversary of the fall of the Berlin Wall, which essentially signaled the end of the Cold War. Right now, I suspect, the Web's impact is not viewed in the same way as those events. But it should be.

The creation of the Web "is probably going to be remembered more than any individual wars," said Marc Weber, creator and curator of the Internet history program at the Computer History Museum in Silicon Valley. "The printing press is remembered more than any of the big wars that were happening at the time."

We tend to forget that, paying far more attention to the latest hot app like Secret and Snapchat.

"We had these utopian dreams for it, but now it's like any successful public utility," said Geoffrey Nunberg, a linguist and adjunct professor at UC Berkeley's School of Information. "We only tend to notice it when it breaks down."

But the Web should be marveled over on its birthday even as we ignore it like a background tune that is always playing, or yell at it when a Web page slowly loads.

The Web made the Internet accessible. That's what we are celebrating today on its 25th birthday. Even as we take the Web for granted, it is something we now can't live without.

Contact Michelle Quinn at 510-394-4196 and mquinn@mercurynews.com. Follow her at twitter.com/michellequinn.