You are browsing a favorite website when a popup window appears. You close the window to continue browsing, and another popup appears. Later on, you realize that several windows have opened because of these popups. Annoying, isn't it?

Popup windows are another type of online advertising on the internet. Its purposes include increasing website traffic, which is the number of people who visit a particular website; and to capture email addresses without any prior knowledge from the person who is browsing the website.

Advertising supported websites make up the large chunk of popup users. These websites previously used banner advertisements (banner ads, these are the advertisements on top of a browser window) to generate huge profits.

They take advantage of internet users who have less experience in dealing with internet advertisements by offering gifts or items that go with any particular purchase. Unaware users bite into the bait, and before they know it, they are also being charged for the "gift" ? that went with their purchased item.

As customer interest in banner advertising decreased, many internet-based vendors began to think of developing more effective advertising methods. By then, popup advertisements started annoying many internet users.

Popup windows are the windows which appear when website browsers open a new web browser to display various contents such as advertisement for product subscription, opinion surveys, and free download.

This window is often times generated by Javascript, but can also be generated by other means. Some of the new popups are created using Flash which contains animations, while others are created using DHTML, so the popup appears before the browser screen.

Many internet advertisers love popup ads because of their nature. Popups are hard to ignore as they appear first before the main browser window. This characteristic makes it even better than the previous stationary banner advertisements.

Popups are also loved for their high clickability rate as more people click on them because of their ability to tickle the interest of internet users. It is also shown by recent studies that the click-rate of popup ads is twice as that of the banner ads. Between January and September 2002, the number of popups increased from 1.2 billion to 4.9 billion.

Among the top users of popup ads are websites promoting pornography and violence. Not only do these popups advertise adult content, they also set off multiple windows.

As the user closes a window, a another window appears, initiating another set of windows, and sometimes this happens indefinitely. Users call this "java trap" ?, or "spam cascade" ?. There are, however, processes which can produce popup windows such as spyware programs.

"Mousetrapping" ?, a variation of the popup, fills the whole screen with its content, removing the menu bars and other features which allows the user to close the window.

Another variation is called the pop-under advertisement wherein a new browser window is opened behind the active window. Pop-unders are less annoying to a user, but are only seen when the main browser window is closed, making it difficult to find out which website opened them.

Recently, however, many internet users have expressed their annoyance over the massive number of popup windows they encounter while browsing.

As a response, more companies have reduced or removed popups from their websites, and internet browsers such as Microsoft Internet Explorer, Mozilla, Netscape, America Online, Camino, Opera, and Safari, are providing features to block popups. Additional programs to block popups and spyware are also available.