This is a concept from the study of chemistry. Atoms can be bonded (meaning stuck together) to each other in two different ways:
- A covalent bond happens when atoms share electrons between them.
- An ionic bond happens when one atom removes electrons from another atom, and they are attracted to each other as a result.
If you'd like to understand ionic and covalent bonds better, you can watch this video lesson:
This topic doesn't come up in conversation much outside of science classes.