In a heterogeneous mixture, the individual components do not blend perfectly together. They remain physically separate in their own distinct regions. If you take a sample from the top, it might look very different from the bottom.
The properties of the mixture change depending on where you look. Because the parts stay separate, you can easily pull them apart using physical methods. You can use a filter to catch solid chunks out of a liquid.
You can also just let a heavy substance settle to the bottom over time. A muddy puddle is another great example because the dirt settles to the bottom. The chemistry word homogeneous is the exact opposite of this term.
A homogeneous mixture looks completely identical no matter where you sample it. Chemists also use the word heterogeneous to describe certain chemical reactions. A heterogeneous reaction involves chemicals that are in completely different physical states.
For example, a solid metal might react with a liquid acid. This concept is extremely important in huge factories and chemical plants. It allows workers to easily separate expensive solid catalysts from liquid products.
