What is Hook in Programming And Why is it Important

Since Hooking has become a crucial concept in computer programming therefore it has become a need of an hour to know what is hook. Hook is basically a place where you can insert coding in order to monitor the functioning of a program. This article will help to understand what is hook and the other aspects in relation to hook in programming.

What is a hook?

A Hook is basically a place or an interface present in packaged code which allows you to insert a customized programming in programming.

For example you as a programmer want to provide a code which analyzes the frequency of a particular logic path within the program.

Basically, hooks are given for a prescribed purpose and are documented accordingly for the programmer.  So these are to be used wisely so that it can be used to perform the core of the function of hooking otherwise it may lead to destruction or the program. This is also a reason to carefully understand what is a hook.

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Meaning of Hook

In computer programming, programmers use a technique to modify or extend the behavior of applications, operating systems or of other software components through intercepting calls or messages or events occurring within such components. Code which is used to perform intercepting such call messages or events is called hook.


Hook function is also used by browsers to make it simple for antivirus software in order to scan downloads. The interesting fact about the same is that when it starts a download then it says “hey anyone listening, I’m starting a download!’ and thereby other programs can also react to the same. You won’t be able to understand this procedure unless you know what hook is.

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Why is it important to know what is hook?

1.  Hooking allows a programmer to change the behaviour of a program. Code in a program gives this feature to modify the original behaviour of a program without changing the codes of corresponding class. And all this is done by hook function. Thereby the need to understand what hook arises.

2.  Secondly, hook function helps to add new functionalities to applications.

3.  It ensures the inter-communication between the other process and messages of the system.

4.  The major aspect of knowing what is hook is that it may degrade the performance of a program due to increase in processing load. And it is required to perform these functions for each message. Thus, it should be cautiously handled and it must be installed only when it is much needed and thereby it should be removed as soon as possible.

5.  If we say in common parlance what is hook then it is a kind of function which allows a programmer to modify or extend the behaviour of the existing system or program.  If we can extend any chrome or browser then it is because of hooks in such chrome or browser.

In a nutshell, if we say what is a hook then it is like you fix your program in such a manner that if any particular thing happens in such a program then it will inform you.  That is why some developers put this function intentionally.

What is Hook as Design Patterns?

One interesting fact about the hook is that now all the design patterns typify semantics for hooks. Whereby, semantics is generally expressed in the hooks with the name of “in the command”. The main function of Hook as Design patterns is to implement subsystems of hotspots.

If you are a video games lover then also you should know what is hook as video games are also supported by hooks in action.

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Two concepts of Hooking

It is very important to know the concept of IAT hooking and Inline hooking in order to understand what is hook as it performs the function of hooking in the program.

1.  IAT HOOKING – Import Address Table hooking

In programming, the operating system is responsible for loading executable files into memory on double-clicking or otherwise. Here, loading means to read and interpret the bytes of the program on disk. Loading also finds out which part of the program will go where and how the file will be saved in the program.

A running program is basically a simple set of instructions and data which are loaded in memory of the program and it consists of 1 thread executing instructions.

2.  Inline Hooking

Inline hooking and IAT hooking are almost similar and the basic difference between the two is that inline hooking writes the malicious functionality into a legitimate DLL instead of misguiding a victim file.

Types of Hooks

 To know more  what is hook we should look into its types. Following are the types of hooks-

1.  Virtual Method Table Hooking

Virtual method is similar to static method. But virtual methods can be modified comparatively as the compiler does not know the address of a particular virtual function when we put it in the code. That is why the compiler builds a Virtual method table to provide a method to search the function address meanwhile. VMT uses more memory and also run faster.

Conclusively, VMT has pointers with memory addresses for interface functioning.  It is required to be performed in order to replace the original memory address with the address of valid hook function. Thereby, hooking performs the vital function in a program.

2.  Hooking API

API stands for application programming interface. This method is used to reprogram the functioning of the operating system; as we can change the parameters of commands by modifying the action that was performed originally. It also specifies the significance of what is a hook.

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Hook has emerged as an important tool for program developers as they can modify and extend the code of the program or system. Hooking is a technique to change the behaviour of the operating system or of other Softwares. Thus, it helps them to monitor the functioning of a program accordingly for example debugging. After understanding the concept and significance of hook in programming. We have learned how important it is to know what is hook in today’s time.

Frequently Asked Questions

What is the main purpose of hooking in programming?

In programming, the term hooking covers a range of methods used to adjust or augment an operating system’s behavior, apps, or other software parts by intercepting function calls or events or messages passed between software segments.

What is the method of inserting hooks?

Generally, hooks are inserted when the software is already being run, but hooking is a scheme inserted before the app is started. There are two types of hooking, one is Source modification, and the other is Runtime modification.

What is hooking in cybersecurity?

Code hooking is an extremely intrusive coding activity where primarily OS function calls are intercepted by a program to augment or alter their behavior. Antivirus does this all-time when they find a piece of malware or when some modified routine is behaving badly.

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