“I am lead to believe this is where your mother met your father.”
edit Brief history of toolbars
User interfaces have a long and painful history, so it would be extremely long and painful to repeat everything here. But the fundamental roots of toolbars can be traced to tool belts which are used to a) carry tools and b) keep your pants up; as it happens, b) is hard due to a), it's kind of difficult when you have tons of heavy tools attached on it.
So, in the dim dawn of graphical user interfaces, someone figured out, "hey, how about we put these application tools on row, here, right on the window, like on a tool belt". The rest is history.
There really hasn't been much development of toolbars. Well, at one point, toolbars had row of icons with helpful text under them. Icons used to be helpful. Then aforementioned Bernard Gui, inventor of GUIs, noted that icons are Greek Catholic heresy, and threatened to burn everyone on stake. Thus, Icons were replaced with Fuzzy Fashionable Pictures that are, actually, still called Icons; however, the primary difference between Fuzzy Fashionable Pictures and real icons is that Icons tend to be kind of recognizable and FFPs are just artsy-fartsy stuff that tries to reduce the very metaphorical essence of some abstract action to a 16x16 bitmap, while usually failing. I mean, ever figured out what the heck all those buttons in Word do? Me neither.
Well, that would have still helped. Then someone figured that the text under the icon just takes space. So they left the Icons (FFPs). Then they noted the icons were altogether too big, and still too clear for people to comprehend. So they shrunk them further. They only backed down from their idea of removing tooltips too, because someone threatened to kick their teeth in.
edit Theoretical Use
Pope John XXII said something along the lines of "Vearieye Useyful for All Goode Christians to Quickeely doo Whateever they Wante, Amen", but regrettably, Gui's robed goons managed to completely mess things up. And anyway, put it this way, no one had a clue what he was saying any of the time. The toolbars spread through the world like black plague.
In mid-1300s, and with heavy international collaboration, zen buddhist monks finally figured out what the heck the Computers were supposed to do, and the nefarious goals of Bernardo Gui and the Inquisition. Computers, they found, Waste Time. GUIs, they discerned, Waste Thought. Toolbars, they cleverly noticed, Waste Space.
The primary use of toolbars has not changed since. Except that now that toolbars are finally associated with spyware, the monks at University of Tibet have figured out that the toolbars Waste Power as well.
edit Modern Practical Use
Toolbars today are most commonly associated either with useless search engines or Spyware. Every single toolbar made these days has only one goal, which is to make everyones' lives a complete and utter misery.
Toolbars generally come accompanied by 20 million adverts offering cheap Swedish Lesbians.
A toolbar Wastes about 20 pixels of horizontal space and God knows how many horizontally, but usually just a little bit more than how wide you tend to keep your windows. In this space, they've usually crammed a pop-up blocker, weather report display (for those without a flexible enough neck), search box, giganto-huge-ass logo, a "privacy protection" feature, and no indication that your browse history, keyboard activity, and mouse clicks on the browser window are not being sent to a web site for further analysis, completely non-anonymously.
Toolbars often come with Customization options. A common toolbar will allow the user to choose between what adverts pop up (between Swedish Lesbians and Cheap Polish Immigrants) and if they pop up every 1 nanosecond or 0.37456 nanoseconds.