This document contains comments about the document "Nuclear binding energy" in Wikipedia
• The text in italics is copied from that url
• Immediate followed by some comments
In the last paragraph I explain my own opinion.

### Introduction

The article starts with the following sentence.
Nuclear binding energy is the energy that would be required to disassemble the nucleus of an atom into its component parts. These component parts are neutrons and protons, which are collectively called nucleons.
It is the same energy in principle as when you want to assemble or build the nucleus.
The mass of an atomic nucleus is usually less than the sum of the individual masses of the constituent protons and neutrons (according to Einstein's equation E=mc^2) and this 'missing mass' is known as the mass defect, and represents the energy that was released when the nucleus was formed.
This sentence is not correct: The (binding) energy of an atomic nucleus is usually less than the sum of the individual (binding) energies of the constituent protons and neutrons and represents the energy that was released when the nucleus was formed in the form of radiation.
The fact that there is also a mass defect using the equation E=mc^2 is physical of no importance.

### 1. Introduction

Nuclear binding energy is explained by the basic principles involved in nuclear physics.
Correct.

### 1.3 Physics of nuclei

The nuclei of atoms are found in many different sizes. In hydrogen they contain just one proton, in deuterium or heavy hydrogen a proton and a neutron; in helium, two protons and two neutrons, and in carbon, nitrogen and oxygen - six, seven and eight of each particle, respectively.
A helium nucleus weighs less than the sum of the weights of its components. The same phenomenon is found for carbon, nitrogen and oxygen. For example, the carbon nucleus is slightly lighter than three helium nuclei, which can combine to make a carbon nucleus. This illustrates the mass defect.
The third sentence should be modified as follow:
The binding energy of helium nucleus is less than the sum of the binding energies of its components. The same phenomenon is found for carbon, nitrogen and oxygen. For example, the binding energy of carbon nucleus is slightly less than three helium nuclei, which can combine to make a carbon nucleus.
The sentence: "This illustrates the mass defect" should be removed.

### 1.3.1 Mass defect

Mass defect is the difference between the mass of a composite particle and the sum of the masses of its parts.
The problem is: this is only a mathematical exercise.
The "mass defect" can be explained using Albert Einstein's formula E = mc^2, expressing the equivalence of energy and mass. By this formula, adding energy also increases mass (both weight and inertia), whereas removing energy decreases mass.
All this is purely a mathematical exercise. The issue is what is energy, how do you add energy?