* Electron-donating group: The hydroxyl (-OH) group in phenol is an electron-donating group. This means it increases the electron density in the benzene ring, making it more susceptible to electrophilic attack.

* Resonance stabilization: The lone pair of electrons on the oxygen atom of the hydroxyl group can participate in resonance with the benzene ring, further increasing electron density and activating the ring towards electrophilic substitution.

In contrast, benzene is a relatively unreactive aromatic compound. It requires harsh conditions and a strong electrophile like bromine in the presence of a Lewis acid catalyst (like FeBr3) to undergo bromination.

Therefore, phenol undergoes bromination readily at room temperature without the need for a catalyst. This is because the electron-donating hydroxyl group activates the ring, making it much more susceptible to electrophilic attack by bromine.