What is the Difference Between Linker Loader and Compiler? with Proper Definition and Brief Explanation

The main difference between the linker loader and the compiler is that the linker combines one or more compiler-generated object files into a single executable file. Meanwhile, a loader places programs in memory and prepares them for execution, while the compiler converts the source code to object code.

A computer program is a collection of instructions that perform a specific task when the computer executes it. System software is a type of computer program that provides a platform for other software. Linker, loader, and compiler are three software systems associated with computer programming.

Key Areas Covered

1. What is a compiler?
     – Definition, Functionality
2. What is a linker?
     – Definition, Functionality
3. What is a Loader?
     – Definition, Functionality
4. What is the difference between Linker Loader and Compiler?
     – Key Differences Comparison

Key terms

Compiler, Linker, Loader

What is a compiler?

A program is a set of instructions to perform a certain task. It is also known as the source code. The programmer can understand the source code, but the CPU cannot understand it. Therefore, it is necessary to convert the source code to a machine understandable format.

                                                                Figure 1: Compiler

A compiler is special software that is used in this process. Convert source code to object code. This object code is intermediate code. The CPU cannot execute it directly.

What is a linker?

After converting the source code to the object code, the linker performs the linking task. It takes one or more compiler-generated object files and combines them to produce an executable file.

                                                                     Figure 2: Linker

In addition, it combines the object codes with the libraries. For example, in a C program, if there is a sqrt() function to compute the square root of a number, the linker links the program with the math library. Finally, the CPU can read and understand the generated executable file. Therefore, the CPU can execute that file to perform the task defined in the program. 

What is a charger?

A loader locates programs in memory and prepares them for execution. It is an important component when starting a program. It includes tasks like reading the contents of the executable file and putting the file into memory. In addition, it performs the necessary tasks to prepare the executable file for execution. After the upload is complete, the operating system starts the program by passing control to the uploaded program code.

                                                              Figure 3: Compilation

Most operating systems support loaders for loading programs. Most systems have the loader located in memory, while others that support virtual memory have the loader in a pageable region of memory.

Difference between linker loader and compiler


A linker is a computer utility program that takes one or more object files generated by a compiler and combines them into a single executable file. A loader is part of an operating system that is responsible for loading programs into memory. A compiler is software that transforms computer code written in one programming language (source code) into another programming language (target code). So this explains the main difference between linker loader and compiler.


Also, a linker combines various object codes and links them with libraries. Meanwhile, a loader prepares the executable file to run, while a compiler transforms the source code into object code. So, this is the difference between linker loader and compiler in terms of functionality. 


In summary, the difference between linker and compiler loader is that a linker combines one or more compiler-generated object files into a single executable file and a loader places programs in memory and prepares them for execution, while that a compiler converts source code into object code.


1. “Linker (Computer Science)”. Wikipedia, Wikimedia Foundation, October 6, 2018, Available here.
2. “Loader (Computing).” Wikipedia, Wikimedia Foundation, October 10, 2018, Available here.
3. “Compiler”. Wikipedia, Wikimedia Foundation, October 9, 2018, Available here.

Courtesy image:

1. “Ideal Compiler” (CC BY-SA 3.0) via Commons Wikimedia
2. “Linker” by Qef: Own work by uploader, based on equivalent bitmap layout by Orderud (Public Domain) via from CommonsWikimedia.
3. “Screenshot-turbo51.com 2016-01-14 18-44-16″ By ���������� – Aho, Sethi, Ullman, Compilers: Principles, Techniques, and Tools, Addison-Wesley, 1986. ISBN 0-201-10088-6 (CC BY-SA 4.0) via Commons Wikimedia

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