HBr, or hydrobromic acid, is classified as a strong acid. This classification means that HBr completely dissociates in water, releasing all of its hydrogen ions (H⁺) into solution. When HBr is added to water, it breaks apart into H⁺ and Br^– ions, leading to a high concentration of hydrogen ions.

The strong acid behavior of HBr is due to its molecular structure and the bond strength between hydrogen and bromine. The H-Br bond is relatively weak compared to other acids, making it easier for the molecule to release its hydrogen ion. This complete dissociation results in a lower pH (usually below 1) in concentrated solutions, indicating a high level of acidity.

In contrast, weak acids only partially dissociate in water, resulting in a mixture of undissociated molecules and ions, which would not be the case with HBr. Similarly, bases are classified as strong or weak based on their ability to dissociate in water to form hydroxide ions (OH^–), which HBr does not do since it is an acid. Therefore, HBr is unequivocally categorized as a strong acid.