Prefix for object in .Net

Control	Prefix
Label	lbl
TextBox	txt
DataGrid	dtg
Button	btn
ImageButton	imb
Hyperlink	hlk
DropDownList	ddl
ListBox	lst
DataList	dtl
Repeater	rep
Checkbox	chk
CheckBoxList	cbl
RadioButton	rdo
RadioButtonList	rbl
Image	img
Panel	pnl
PlaceHolder	phd
Table	tbl
Validators	val

Captcha and Its Applications

CAPTCHA  is a type of challenge-response test used in computing as an attempt to ensure that the response is generated by a person. The process usually involves one computer (a server) asking a user to complete a simple test which the computer is able to generate and grade. Because other computers are assumed to be unable to solve the CAPTCHA, any user entering a correct solution is presumed to be human. Thus, it is sometimes described as a reverse Turing test, because it is administered by a machine and targeted at a human, in contrast to the standard Turing test that is typically administered by a human and targeted at a machine. A common type of CAPTCHA requires the user to type letters or digits from a distorted image that appears on the screen.
The term "CAPTCHA" was coined in 2000 by Luis von Ahn, Manuel Blum, Nicholas J. Hopper, and John Langford (all of Carnegie Mellon University). It is an acronym based on the word "capture" and standing for "Completely Automated Public Turing test to tell Computers and Humans Apart". Carnegie Mellon University attempted to trademark the term, but the trademark application was abandoned on 21 April 2008.
Characteristics: A CAPTCHA is a means of automatically generating challenges which intends to:

• Provide a problem easy enough for all humans to solve.
• Prevent standard automated software from filling out a form

A check box in a form that reads "check this box please" is the simplest (and perhaps least effective) form of a CAPTCHA. CAPTCHAs do not have to rely on difficult problems in artificial intelligence, although they can.

Application of Captchs

·          CAPTCHAs are used in attempts to prevent automated software from performin action which degrade the quality of service of a given system from abuse or resource expenditure.

·          CAPTCHAs can be used to protect systems vulnerable to e-mail spam, such as the web mail services of Gmail, Hotmail, and Yahoo! Mail.

·          It is also used to minimize automated posting to blogs, forums and wikis , whether as a result of commercial promotion or harassment and vandalism.

·          It also performs important role in rate limiting.

The .NET Framework (pronounced dot net) is a software framework that runs primarily on Microsoft Windows. It includes a large library and supports several programming languages like C++,C#(C Sharp) etc. which allows language interoperability (each language can use code written in other languages). Programs written for the .NET Framework execute in a software environment (as contrasted to hardware environment), known as the Common Language Runtime (CLR), an application virtual machine that provides important services such as security, memory management, and exception handling. The class library and the CLR together constitute the .NET Framework.
The .NET Framework's Base Class Library provides user interface, data access, database connectivity, cryptography, web application development, numeric algorithms, and network communications. Programmers produce software by combining their own source code with the .NET Framework and other libraries. The .NET Framework is intended to be used by most new applications created for the Windows platform.

.Net Framework development is started for 1990 by Microsoft with the name Next Generation Windows Services (NGWS). In 2002 Microsoft introduce first version of .Net.

After that many other versions are released like .Net Version 1.1, 2.0, 3.0 etc. Now the latest version of .net is 4.5 was release in 2011.

Features Of .Net Framework

.Net has following features:

• Interoperability
• Common Language Runtime (CLR)
• Language In-dependency
• Base Class Interface
• Portability
• Simplify Development