Acids and bases are two types of substances that have different properties and characteristics. The main differences between acids and bases are as follows:

1. Ionization: Acids ionize in water to release hydrogen ions (H+), while bases ionize in water to release hydroxide ions (OH-).

2. pH: Acids have a pH value less than 7, indicating that they are acidic. Bases have a pH value greater than 7, indicating that they are alkaline or basic. A neutral substance, like water, has a pH of 7.

3. Taste: Acids have a sour taste, such as vinegar or lemon juice, while bases have a bitter taste, like baking soda.

4. Reactivity: Acids are typically reactive substances that can corrode metals, neutralize bases, and cause burns on the skin. Bases, on the other hand, are generally less reactive but can still cause burns and are often used as cleaning agents.

5. Conductivity: Acids are generally good conductors of electricity because they release hydrogen ions, which are charged particles, in water. Bases, too, are good conductors of electricity because they release hydroxide ions, which are also charged particles, in water.

6. Litmus Test: Acids turn blue litmus paper red, while bases turn red litmus paper blue. This is due to the ability of acids to donate hydrogen ions and bases to accept hydrogen ions.

7. Neutralization: When an acid reacts with a base, they neutralize each other, forming water and a salt. This reaction is known as neutralization.

Overall, acids and bases are chemically opposite in nature and have different properties and effects on substances they come into contact with.

An acid is a substance that produces hydrogen ion as the only positive ion when mixed with water. A base is a substance that produces hydroxyl ion as the only negative ion when mixed with water. An acid is a species that can release/donate a proton to another species.