What is Computer?

A computer is an electronic device that performed numerical calculations as well as logical operations. It is a general purpose device that can be programmed. Computer accepts information and manipulates it for some result based on a program or sequence of instructions on how the data is to be processed. Computer can not do anything without a Program.  Now a days computer can be used to type documents, send email, play games, and browse the Web. You can also use it to edit or create spreadsheets, presentations, and even videos. 
 

The word computer is made from the Latin word 'computare', this means machine for calculations. Charles Babbage is considered to be  'father of the computer'. He was the first person who designed mechanical computer that eventually led to more complex designs.

The basic components of a modern digital computer are: Input Device, Output Device, Central Processor Unit (CPU), mass storage device, and memory.

HTML email in PHP

PHP's mail() function allows you to send HTML emails directly from a script.
<?
$to="abc@yahoo.com";
$subject="mail subject";
$body="mail body";
$headers  = 'MIME-Version: 1.0' . "\r\n";
$headers .= 'Content-type: text/html; charset=iso-8859-1' . "\r\n";      
$headers .= 'From: yourname <no-reply@yourdomain.com>' . "\r\n";
mail($to, $subject, $body,$headers);
?>

The above code is enough for sending HTML email to anyone by using PHP language. The code is very simple and tested.

CC and BCC in email

 

CC means Carbon Copy. If you want to send same copy of your email to many person then you can use this field. You don't need to put all the email addresses in the 'To' field but the email address will be appeared to others as well. For example, if you CC roy@xyz.com and rob@xyz.com on an email, Roy will know that Rob also received the email, while Rob will know that Roy also received the email.

BCC means Blind Carbon Copy. This works as same as CC but the only difference is that other's email address will not be displayed to the recipients. So the recipient will not be aware of the fact that whom have got the same email. For example, if you BCC roy@xyz.com and rob@xyz.com on an email, Roy will not know that Rob also received the email, while Rob will not know that Roy also received the email. So the BCC list is secret – no one can see this list.

In case of reply, all the CC users will receive the reply email but in BCC only the original sender will receive the email.

The term comes form Carbon Paper. In old days, carbon papers were placed between two pieces of paper and while writing in top paper, the copy of writing was placed in second paper by the ink of carbon paper. As a result, a duplicate copy of document can be obtained. In CC or BCC a copy of original email is sent to others.
The To and CC fields work similarly but it is better to use CC in formal email.

PDF: What is PDF

PDF means Portable Document Format. It is a standard for document exchange. Adobe Systems is creator of this file format in 1993. Adobe cofounder John Warnock launched the paper-to-digital revolution with an idea he called The Camelot Project. Camelot’s goal was to give organizations the tools needed to "capture documents from any application, send electronic versions of these documents anywhere, and view and print these documents on any machines." PDF is used for representing documents in a manner independent of application software,  hardware, and operating systems. Each PDF file encapsulates a complete description of a fixed-layout flat document, including the text, fonts, graphics, and other information needed to display it. Adobe Systems invented PDF technology to smooth the process of moving text and graphics from publishers to printing-presses. PDF documents can be opened on any popular platform like Linux, Windows, Mac  and the  look will always be identical. PDF documents have a .pdf file extension. Now a days it is extensively used in magazine articles, product brochures, or flyers in which to preserve the original graphic appearance online.

You need PDF reader to read PDF file. There are many pdf reader available. Suppose Adobe Reader, PDF Reader, Nitro PDF Reader etc. and to create a PDF file you must need PDF writer like Adobe Acrobat Writer, PDF writer etc.

Initial release: June 15, 1993
Standard     ISO 32000-1
 

Alpha Channel

Alpha channel......
Few days ago, I wanted to put an image while generating PDF by using FPDF, I got an error that said 'Alpha channel is not supported'. I got stunned and started to think what is it?

In Computer Graphics , Alpha channel is used as an opacity channel. Alpha channel will ensure that how much your image will be transparent or not and it is an additional channel that can be added to an image which contains transparency information about the image. Depending on the type of alpha it can contain various levels of transparency. In PNG/TIFF alpha channel represents up to 256 levels of transparency.

A 32 bit graphics system contains four channels where three 8 bit channel are for Red,Green,Blue (RGB) and one8 bit alpha channel. So alpha channel is simply use of RGB model with extra information. Alpha channel values can be expressed as a percentage, integer, or real number between 0 and 1 like RGB parameters.If a pixel has a value of 0% in its alpha channel, it is fully transparent (and, thus, invisible), whereas a value of 100% in the alpha channel gives a fully opaque pixel .
The following are the file type that support alpha channel:
    * TIFF     * TGA     * PNG     * PSD (Photoshop)     * GIF (special alpha)

Bottleneck

The term 'Bottleneck' that we are going to discuss is not the neck of a bottle rather it tells a different thing. Bottleneck is a phenomenon that impede or slow down the performance of a system. For instance, a computer program may spend 80% of its time in a small loop deep in the code, and the remaining 20% of the time on the rest of the code; the small loop then is a bottleneck. Pertaining to a business, a firm will address the 'bottleneck' that is limiting production. Bottleneck is a familiar terms in every section of knowledge suppose in Engineering, Economics, Project Management etc.

In computer programming, tracking down bottlenecks is called performance analysis. Reduction is usually achieved with the help of specialized tools, known as performance analyzers or profilers. The objective being to make those particular sections of code perform as fast as possible to improve overall algorithmic efficiency.