What is it about Yahoo that makes it worth buying?

The company is said to be exploring a sale of some of its most important properties, which aren't growing as quickly as some investors have hoped despite a years-long effort by chief executive Marissa Mayer to engineer a revival of the Internet giant's brand.

Now, that question may be the key to understanding the parlor game of rumor and conjecture swirling around the company. Depending on which speculating analyst you talk to, Verizon, Microsoft, Time Inc., Comcast, AT&T, and even IAC - the company that owns Tinder, OkCupid, and Match.com - could all jump in as potential buyers.

(Comcast declined comment Thursday when asked by an Inquirer reporter if the company was considering a bid to buy Yahoo. The Philadelphia-based cable and media giant has invested this year in digital-media companies such as Vox and BuzzFeed through its subsidiary NBCUniversal and in 2014 acquired Freewheel for a reported $320 million. Freewheel, a technology company, places ads on streamed online video.)

To be specific, what we're talking about is a possible sale of Yahoo's "core business," but even that term belies the dizzying range of things that Yahoo actually does. Is it a search company? A media company? An advertising company?

In truth, it is all of those things, which is one reason we have seen so many names come out of the corporate woodwork. But it turns out there's one metric that makes Yahoo really attractive: the number of eyeballs it commands on a monthly basis.

This might seem obvious in an era in which click bait and traffic seem to rule with an iron grip. But if you take Yahoo apart piece by piece, you start to understand why snapping up the company would benefit some firms more than others.

Take Microsoft. It actually tried to buy Yahoo before, in 2008. The objective then was to head off Google's rapid rise. As Business Insider put it: "Microsoft was worried about Google dominating a new market, search. Microsoft tried to build its own competitor, Bing (then known as Windows Live Search), but it didn't take off with users. So Microsoft figured it would buy the No. 2 player, Yahoo, and combine its search and search ad business with Microsoft's."

Fast-forward to today, and Bing is no longer lagging behind Yahoo. In fact, what you have is a market in which Bing actually covers more than 20 percent of search, compared with Yahoo's 13 percent. Both have been helped, no doubt, by a joint partnership on search.

Combining the two might get Microsoft a bit closer to Google (which commands 64 percent of the market), but it still wouldn't be within striking distance. And Microsoft would also be inheriting all of Yahoo's other Internet businesses, potentially slowing the company down as it tries to execute a shift toward offering more cloud services, especially for corporate clients.

But let's shift to some of the other names that have been floated. Three are providers of fixed or mobile Internet - four, if you count Softbank, the Japanese parent company of Sprint. That isn't a coincidence; Internet providers increasingly view original online content as the way to turn their networks into cash cows. Carrying data over simple pipes is no longer as lucrative as before.

We've seen this play out before to different degrees, both with AT&T's acquisition of DirecTV and with Verizon snapping up AOL.

"There are a lot of different networks looking for good content," said Chip Pickering, chief executive of INCOMPAS, a telecom-industry trade group.

Inquirer staff writer Bob Fernandez contributed to this article.