Temperature
One of the easiest ways to see the effects of temperature on matter is the phase changes of water. When the temperature is low molecules move very slowly and form structures that stick together. As heat is applied the water molecules start to move faster, bounce off each other and turn to a liquid. If the temperature continues to increase the molecules will move so fast they move freely and turn into a liquid. If this rise in temperature continues they will move so fast that they turn into a gas. The same principal happens when the process is reversed and water turns into ice. The animitation on this website demonstrates the effects of temperature on water. If you lower the temperature you can see the water molecules slow and turn into an ice, but if you raise the temperature you can see them turn into a liquid and gas.
http://antoine.frostburg.edu/chem/senese/101/solutions/faq/why-salt-melts-ice.shtml

Molten rock is also an example of the effects of temperature on matter. When rock reaches its melting point, it turns into a liquid and can move.

Pressure
In most substances a rise in pressure affects the melting and boiling points. Typically a raise in pressure raises both the melting and boiling temperature.

Application
An understanding of the effects of temperature and pressure are useful because they can change how matter reacts. Knowing how these will effect a substance can help you obtain a desired result.