Some technologies are like Sylvester Stallone in Rocky, a rank outsider who ends up basking in glory.
But more often than not they end up like Mickey Rourke in The Wrestler, washed up and mourning their time in the spotlight.
In their prime, these 10 titans seemed unbeatable.
Now they're either dead, dying or in their dotage.
In the 1990s, "web browser" meant Netscape Navigator. Worried that the internet would kill its software business, Microsoft went on the attack. Netscape didn't have the manpower or the money to fight back for long, and while Netscape's DNA lives on in Firefox the browser was belatedly buried in 2008.
ICQ invented Instant Messaging as we know it back in 1996, and AOL bought parent company Mirabilis in 1998. Like most good ideas ICQ was quickly copied, and today it's just another chat program.
3. Pegasus Mail
Pegasus sent its first email in 1989. As sole creator David Harris writes, "it dates from the time when the internet was a community rather than just a highway - a time when people helped each other without worrying too much about who was going to pay for it." Microsoft's bundling of Outlook Express with Windows and Outlook with Office essentially wiped our not just Pegasus, but most established email programs.
4. Sinclair Research
Men - and it's mainly men - of a certain age go misty-eyed at memories of the ZX-81 and the Spectrum. For a while it seemed that the future of technology was British, but the wheels came off with 1984's business-orientated Sinclair QL. Shipped long before it was actually ready, it was a disaster from which Sinclair never really recovered. The firm sold its computer business to Amstrad in 1986. Speaking of which...
Amstrad was Britain's Dell, selling word processors and then fully-fledged PCs in the 1980s to great acclaim. The PCs were cheap and, if we're honest, nasty, but they sold by the truckload. Amstrad stumbled when hard disk problems forced it to recall its second generation PC2000 series in 1989, and subsequent adventures with laptops, PDAs and the em@iler weren't successful. Today Amstrad is probably best known for former chairman Alan Sugar's role in the Apprentice and the Sky+ boxes it makes for parent company BSkyB.
Before Google, AltaVista was the search engine for internet aficionados - but Google's PageRank, which weighted sites not just on their content but on who linked to them, did a better job. There's no mystery to this one: Google simply built a better search engine.
When we were all running MS-DOS, word processing meant WordPerfect - and version 5.1 was one of the greatest business programs ever written. However, when graphical operating systems came along WordPerfect backed the wrong horse and developed for OS/2 instead of Windows. The belated Windows version was buggy and unpopular, and by the time WordPerfect got it right, Microsoft's Word for Windows had eaten its lunch.
In the 1980s and 1990s Netware was the way of networking PCs, and lots of people - your correspondent included - went on really boring and expensive training courses to become certified Netware administrators. Turns out we should have learnt Windows NT or server Linux instead.
9. CompuServe and AOL
AOL and CompuServe ruled the early Internet, but they didn't see the World Wide Web coming and spent too long trying to keep their users inside their own walled, pay-as-you-go gardens. These days AOL is primarily a publisher, while CompuServe is an AOL-owned ISP.
The future of home entertainment comes down a pipe, not in a box - and for storage, flash memory is faster and more spacious. Just look at the way prices have plummeted in recent years. DVD is dead. It just doesn't know it yet.
Now read Five phones we'll never forget
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Writer, broadcaster, musician and kitchen gadget obsessive Carrie Marshall (Twitter) has been writing about tech since 1998, contributing sage advice and odd opinions to all kinds of magazines and websites as well as writing more than a dozen books. Her memoir, Carrie Kills A Man, is on sale now. She is the singer in Glaswegian rock band HAVR.