Matter is a physical substance in general, as distinct from mind and spirit; (in physics) that which occupies space and possesses rest mass, especially as distinct from energy, or in shorter words, anything that takes up space.
There are two types of matter, first I'll talk about Pure Substances, which mostly consist of just elements and compounds. To begin with I'll go over elements, which is each of more than one hundred substances that cannot be chemically interconverted or broken down into simpler substances and are primary constituents of matter, like sodium or hydrogen. The other kind of Pure Substances are compounds, a compound is anything made up of two or more different elements like saltwater.
Next I'll talk about Mixtures, the other type of matter, which is a substance made by mixing other substances together, is also made up of two different things, Homogeneous Mixtures and Heterogeneous Mixture. First I'll go over Homogeneous mixtures, Homogeneous mixtures are things made up of similar or the same elements, like oxygen, hydrogen, and many other elements, which can also be solutions. (Solutions are a liquid mixture in which the minor component (the solute) is uniformly distributed within the major component (the solvent).
Water is a Pure Substance because it is made up of Hydrogen atoms only.
The other type of Mixtures are Heterogeneous mixtures, which is something made up of other elements or items that can be separated by physical means, such as salt and pepper (Though it may take a while.), muddy water, and skittles, they can also be suspensions (Suspensions are a heterogeneous mixture containing solid particles that are sufficiently large for sedimentation. Usually they must be larger than one micrometer.) or Colloids (Colloids include gels, sols, and emulsions; the particles do not settle and cannot be separated out by ordinary filtering or centrifuging like those in a suspension.)
Skittles are a Heterogeneous mixture because they are made of many different flavors and colors, and can be separated by physical means.