Vinegar is acidic and contains acetic acid. The pH of vinegar varies by type. Distilled white vinegar can have a pH as low as 2.4, while palm vinegar has a pH between 5 and 6.
Acetic acid is a weak acid, meaning it doesn't fully ionize in water, so it doesn't interact with human tissues at a harmful level at the concentrations found in vinegar. It can damage tooth enamel if frequently consumed.
Vinegar is created by fermenting sugar into alcohol and then converting the alcohol into acetic acid. The variety of vinegar is determined by the initial sugary material. An uncorked batch of wine or uncooked apple juice will turn into vinegar in about a week.
Vinegar can be used in cooking, as a medicinal curative and as a cleaning agent.