Sodium hydroxide (NaOH) is an ionic compound. It is composed of two ions:

* Sodium ion (Na+) - This is a positively charged ion.

* Hydroxide ion (OH-) - This is a negatively charged ion.

These ions are held together by electrostatic forces in a crystalline structure. When sodium hydroxide dissolves in water, it dissociates into these ions, which are then free to move around in solution.