are physical combinations of two or more substances, each retaining its own properties.

The description you've provided refers to a mixture in chemistry. A mixture is a physical combination of two or more substances that retain their individual properties. This is distinct from a compound, where substances combine chemically and lose their individual characteristics.

There are two main types of mixtures:

1. Homogeneous Mixtures: These mixtures have a uniform composition throughout. An example is saltwater, where the salt is completely dissolved in water.

2. Heterogeneous Mixtures: These mixtures do not have a uniform composition. An example is a salad, where different ingredients can be easily identified and separated.

In mixtures, the components can be present in varying proportions, and they can be separated through physical means such as filtration, distillation, or sedimentation, without involving any chemical reactions. This characteristic is fundamental in understanding the versatility of mixtures in both everyday life and scientific applications.