The problems Active Server Pages solve can be solved at the client browser. You can do a lot of server work at the client. This means you can do a lot of programming at the client browser. Active Client Pages is defined as the production of HTML pages at the client computer by the browser using web technology. Active Server Pages is abbreviated ACP.
The secret of Active Client Pages lies in the fact that after the first page has been downloaded by the browser, other pages or data are downloaded in advance in the background, without the user knowing, and stored in an HTML master page (or frameset). This master page (or frameset) is the first page downloaded.
By the time the user would have finished dealing with (reading) the first page, the information for the next few pages would have arrived at the browser. When the user needs the next page, the browser displays it from the store (master page).
Consider this scenario: you are the manager of a big shop and you have your computer in front of you. You decide to look at the list of customers you have. Next you choose a particular customer to see the transactions he has carried out. Then you close the program you were using. That is a session.
Consider this other scenario: let us say you want to do shopping online. You want to buy a laptop computer, so you open a page that has categories of laptop computers. You click a category, and you see the different individual laptop computers. You choose one and click its Add to Cart buttons. A new page appears, and then you type in your credit card details; finally, you click send. That is also a session.
A related sequence of activities you do on your computer is a session.