The ability to exert a force that causes an item to move is what is meant by the definition of energy as the "power to accomplish work." Even though the definition is unclear, the meaning is clear: energy is simply the force that moves things.

Potential energy and kinetic energy are the two categories of energy. The best way to think of them is that kinetic energy happens during an activity, whereas potential energy happens before it. Think about raising your physics text in the air. With its elevated location, it has the potential to fall. The potential energy is transformed into kinetic energy, or the energy of motion, if you drop the textbook.

Several distinct types of energy exist. Many of the more well-known forms include:

mechanical energy: the moving force behind machinery
chemical energy: derived from anything that undergoes chemical reactions to provide us with heat or sustenance, such as wood, coal, oil, food, etc.
muscular energy: derived from the chemical energy of the food we eat
thermal energy: converted from heat, such as the steam in a steam engine or heat of exploding gases in a combustion engine
light energy: some organisms, mostly plants, derive their energy from the sun in a process called photosynthesis
electrical energy: an electric charge associated with power, magnets, and electrical currents
nuclear energy: energy released by atoms and converted to heat, then to electrical energy

The Law of Conservation of Energy is perhaps the most significant law to remember when researching the flow of energy. Simply expressed, since the world's supply of energy is finite, it can neither be created nor destroyed. Thus, when anything loses energy, it doesn't actually vanish; instead, it's transferred to another object.

It's important to keep in mind that no energy transfer is 100% efficient. There will always be some energy lost as heat and sound.

When considering the significance of energy, the most important question to ask is, “Which process on Earth doesn’t involve energy?” Energy is present all around us - even in us - all the time.

Energy drives every form of movement. Walking, running, and biking use chemical energy – derived from the food we eat – to fuel our muscles and keep us moving. Trains use either electrical energy, or a combination of thermal and chemical energy, generated from fossil fuels. A sailboat uses mechanical energy, as it is pushed by the wind. Just like wind energy can push a sailboat, the wind’s mechanical energy can also be converted into electrical energy using a wind turbine.

Although we have understood the many aspects of the physics of energy for a long time, humans are still trying to create better and more efficient processes to harness and use energy!