Web Pages are created with HTML
HTML files or web pages are plain text (ASCII) tiles with a lot of tags. These tags are the building blocks of HTML. The tags help document and displaying visual features such as font size, color, italics etc. The tags are also used in creating hyperlinks andembedding images, sounds, video and other multimedia content. HTML tags come in pairs (most of the times); there is a starting and a closing tag. Tag names and tag attributes are enclosed in < /> signs.
Let us look at a simple tag - The Bold tag that displays text in bold.
The starting bold tag is <B> and the ending tag is </B>. Any text enclosed between these is rendered (displayed) in bold by the browser. Remember all closing tags have the extra slash
(/).
Web Browsers
Though the World Wide Web is a part of the Internet, it serves as an importantinterface through which all of the net can be accessed. This interface to the Internet is the browser. The browser displays the HTML files using the instructions in the tags. In addition, the browser can also display images and video.
The web has grown tremendously over the few years and provides a vast range of experiences including video, multimedia presentations, real-time collaboration, interactive pages, radio and television broadcasts. With the use of programming languages such as JavaScript. VBScript, Per!, PHP, ASP, Java. VRML, the functionality of the web is being increased. The pages on the web can also be linked to databases to provide dynamic content to the visitor. This feature attests the active and energetic nature of the web.
Data transfer over the web and client-server interaction
Data transfer over the Internet starts with an event.
The event can be of human origin, for example, you start the browser (a clientprogram) on your computer and request for some information, say an HTML file, located on a remote computer. There are two important ways in which information is requested from a browser, a hyperlink is clicked or a URL is entered in the "Address" or "Location" field.
The event can also be generated from the instructions in a program. Thus, we can automate uploading and downloading of files (data transfer) with the help of a program.
Let us suppose you have requested for an HTML document from a remote computer using a web browser. The browser searches for the remote computer and on locating it, passes the request to a program called the server running on this distant computer. The server then checks up your request and tries to locate the HTML file on its hard disk. On finding it, the server sends this file to your computer. If this HTML document has embedded image, video, and/or sound files, the information and the content of such files are also passed to the browser.
On receiving data from the server, the client which is a browser in our case, starts to display the HTML page. The client holds the sole prerogative on document display, with no involvement from the servers' side. Once it sends the data to the remote computer, the server, so to say, washes its hands off it. On receipt of all requested data, the client-server connection is lost. Thus, the next time this client asks for some information from the server, the server will treat it as a new request without any recollection of previous requests. This means that client-server interaction is "stateless" with every new request generating a new response. Email - How does it work? Email client and programs
Email is the most used application on the Internet. Emails allow users to communicate with each other almost instantly. Daily millions of emails are sent from one part of the globe to the other. You can receive and send emails from all systems whether it is a Windows PC or a Unix machine (even my cell phone allows me to send one!). Employing MIME, you can send video, pictures or sounds along with text messages via email.
Each email account has a unique address. A general format for an email address is:
Each email message consists of a header and a body. The email header has the following information:
· Recipient email address
· Senders email address
· Email address of the people to whom a carbon copy (Cc) and blind carbon copy (Bcc) is been sent.
· The subject line The main email message resides in the email body.
Emails can be sent by typing the recipients' email address in the 'Send to' field. Any additional recipients can be specified using the Cc or the Bcc.
File Transfer Protocol - FTP
The File Transfer Protocol is an excellent method to transfer (download and send) files from one computer to the other over the Internet. Though you can transfer files using email, it is not a good choice especially when the file size is large or when you need to transfer several files. The objectives of FTP are to:
· promote file (programs or data) sharing
· efficiently transfer data from one computer to another
· provide a common platform for file storages among different hosts
HyperText Markup Language (HTM,L) basics and the format of HTML tag
. The word HyperText means that some text in the HTML document carries a link to a different location. which can be on the same page or another page. On clicking this 'hot spot' the viewer istransferred to that location. The word Markup means that specific portions of a document are marked up to indicate how they should be displayed in the browser.
The main purpose of HTML is to describe the structure of a document and this structure can consist of tables, lists, links, blocks of text such as paragraphs etc. However, the formatting of HTML document, or how the HTML document should look like, depends solely on the browser. It is common knowledge that even different versions of the same browser do not display HTML alike. Thus, HTML was not designed for document layout - it simply describes thestructure of the document. So over the years, web developers have been employing several tricks to layout web pages.
Cascading Style Sheets are now supported pretty well by all modern browsers thoughthere are still some differences to be ironed out.
An HTML document is a plain ASCII text file and, typically consists of a HEAD and a BODY. The head encloses style attributes, meta tags and any client side scripting while the text for the document along with formatting rules are placed in the body section.
Each HTML document begins with the <HTML> tag and ends with </HTML> tag. The head is enclosed in <HEAD> and </HEAD>. Similarly all the elements inside the HTML body section are encased in <BODY> and.</BODY>.
There are hundreds of HTML tags and some of these are proprietary, which means that only some browsers recognize them. HTML tags come in a pair - there is a starting and an ending tag... though there are some exceptions to this rule.
An HTML tag is easily recognized because it is enclosed between < and > signs. Theformat of a tag is as follows:
<TAG-NAME [ATTRIBUTE1= [value1]] [ATTRIBUTE2= [value2]]...> Some text
</TAG-NAME>
As you will notice, the ending tag differs from the starting tag by a slash (/).
Also, most HTML tags also have attributes associated with them. These attributes change the properties of the tag. Most of the attributes also need a value through which formatting is achieved. A tag can have many attributes. These attributes are placed inside < and > signs of the starting tag. Tags can also be nested to increase the formatting feature of the text enclosed. Finally, inclusion of multimedia content such as images, animation, sound clips, video etc. on HTML pages is achieved by using tags.
