Pop-up Window :
Some sites use a pop-up window that opens suddenly without your knowledge, which leads to other sites or blogs. For those who are not familiar with the pop-up window, they are advertising windows on the web, which work when a web page opens a new browser window inviting you to visit another site. It is often used for promotional purposes. It is easy to add a popup to your blog or site and adding a popup helps in increasing the number of visitors and knowing the useful links inside your site and other external sites.