Cross-Site Request Forgery (CSRF) is a technique that induces authorised users to send a request to a Web app that they have been already authorized against. CSRF exploits take advantage of a Web application's confidence in an authorised user. It is a sort of attack where an end user is forced to do undesired activities on a web app in that they are currently authorised. 

XSS (Cross Site Scripting) occurs when an attacker utilises a web app to transmit malicious script to a separate end user, often in the style of a browser based scripts. The vulnerabilities which permit such exploits to operate are fairly common, and they occur whenever a webservice incorporates input validation inside the output it creates without verifying or encapsulating it.

SQL injection, often known as SQLI, is a popular attack method that employs harmful Sql queries to manipulate backend databases in order to obtain information that's not supposed to be shown. This info might contain confidential corporate data, users lists, or confidential consumer information.

A denial-of-service scenario is created by bombarding the targets system or networks with traffic till the victim is unable to react or fails completely, prohibiting genuine users from gaining access. DoS attacks could result in significant losses either effort / expense since its services and facilities are unavailable.