Being an old, old personal computer user, it always surprises me what novices don't know. Lately, it seems like many people don't really know what a spreadsheet is for. Back in the day, before computers were entertaining and fun, everyone who nerded-out on PCs knew, and even made an effort to use, spreadsheets.
That's because the VisiCalc spreadsheet, by Dan Bricklin, was the "killer app" that sold thousands of Apple II computers. Why? Because small businesses used it to do bookkeeping and accounting. Unlike accounting software, it was flexible enough to be adapted to doing taxes, business forecasting, budgeting, and pretty much any kind of calculation.
Its strength was that you could set up a sheet to perform a calculation, then you could change some values, and it would automatically recalculate the result. VisiCalc allowed you to do "what-if" simulations, like, "what if I ran out of inventory for a week -- how much money would I lose?"
It's appeal was due to the interface, which resembled a sheet of accounting paper, with rows and columns into which you typed your numbers. Small business owners were intimately familiar with these pads, and I suspect they generally disliked them enough to hire someone else to do the books... but then, would worry about whether they were done right. With the spreadsheet, they could (in theory) get rid of the pads, calculators, pencils, and big erasers.
VisiCalc did well, and spawned imitators, the most famous one being Lotus 1-2-3 by Mitch Kapor, PerfectCalc from Word Perfect, and the least known today being Microsoft's Multiplan. Lotus was challenged by Quattro, then, later, by Excel, which was Multiplan gussied up for Windows.
Back in the 80s, before there was a glut of great software, people who were into computers were eager to use any and all software. So, everyone pirated, and learned, one of the spreadsheets. They'd even try to write their own. Why? Because they were so cool. Never mind that, on the average, most of these software pirates had virtually no use for a spreadsheet, because they didn't have much money.
So, spreadsheets started to show up that did everything from manage phone lists, inventory your comic books, to helping you keep track of Dungeons and Dragons characters. People were using them as databases! (Later on, when the computer folks got interested in databases, they'd make fun of anyone using spreadsheets for that.)
So, there's your second major use of spreadsheets: to hold data.
After the Mac came out, and Multiplan was ported to the Mac, spreadsheets acquired a very nice new feature: charts and graphs. Prior to then, there were special add-on applications that would turn spreadsheet data into graphs, but the Mac, and later, Windows, made integrating the spreadsheet and graphics a lot simpler.
That's the third major use: to generate charts and graphs.
By the late 1980s and early 1990s, the spreadsheet market was on fire. Competition was fierce, and features like "find a solution", and "filter and group my data" got added. Then, Microsoft really wised up, and started bundling Word, Excel, and Access together into a product called Microsoft Office. They also created Microsoft Works. The competitor Claris Works (which was Word Perfect Works) also included a spreadsheet.
Then, Microsoft introduced Windows 95. People upgraded, and then had to buy new software for the much improved platform.
That pretty much spelled the end of the spreadsheet wars, because, unlike the word processor, the spreadsheet wasn't something that the new customers understood. Most people don't really spend time doing bookkeeping, making charts, and maintaining small databases on computers. At least we didn't back then. So, they weren't likely to ever buy a spreadsheet. By bundling Excel, Microsoft basically assured that no competitor could survive.
But, the end of competition also signaled the end of improvement and change, so, spreadsheet technology hasn't really moved forward much in the last ten years. Also, it seems that a large company can sell and support a creaky old spreadsheet for years, profitably; you can still purchase Borland's old Quattro, from Corel.
Due to the end of competition, the big spreadsheet tasks are still: calculations, accounting, managing lists, and making charts.
When a market matures, however, someone from the Open Source movement will try to make their own. There are two major free spreadsheets: Gnumeric and OpenOffice.org Calc. Gnumeric is aimed at scientific uses, but works great as a general purpose spreadsheet. It's more accurate than Excel. OpenOffice.org Calc looks and feels more like Excel, and is a bit slower (though you won't really notice it). These two spreadsheets have the great advantage that they are free.
So, if you were wondering what the heck Excel was for, now you know.
The eBay AngleHow does this relate to eBay? eBay's low cost allows spreadsheet jockeys to sell their sheets online at very favorable prices. If you learn to use sheets, you can buy spreadsheet templates that do 80% of what an expensive app like Quick Books or Sage accounting does, at less than 1/10th of the cost.
There are always a few sheets for sale. Web searches will turn up more. It's a tiny market, but, if you're willing to learn 5% of what a spreadsheet can do, you will be able to save hundreds of dollars in software (and maybe even get your finances in order).
I'm writing a forthcoming ebook on spreadsheets, and plan to sell it on ebay at a low price. Keep an eye out for it.