Online phising or phishing (in finnish kalastelu, also known as Verkkourkinta) is in information technology criminal activity, which aims to gain access to confidential information such as 

• personal data or 
• data, 
• acting as a party entitled to access information. 

The desired information is in particular password or credit card information, which can be used by an attacker to achieve significant financial gains; even a few victims who have fallen for the scam can make the criminal activity profitable. 

Phising usually takes place in the form of e-mail or instant message.

The scam message aims to show as authentic as possible and sent by a reliable party.

The open appearance of e-mail messages helps to deceive the uninformed. 

A message whose sender is indicated as support@yritys.fi is not necessarily connected to the yryttis.fi server in any way. 

From the header information, you can usually see which server the message originated from. 

Some e-mail services, such as the browser version of Gmail, notify the customer when a message comes from a different server than the one indicated in the sender address.