Examination of the cause of an event and the repercussions of the same

Examination of the cause of an event and the repercussions of the same, in 500 words) The effect is what happened; the cause is what made it happen. For example, I wasted five hours typing because the cat turned off my computer. The lost data was the effect; the cat turning off the computer was the cause. An effect can have more than cause. Another cause was that I forgot to save my work. The repercussion of the effect is that I have to retype everything. Please choose a broader topic. Such as, why do we have to wear seatbelts? Why does the earth have an atmosphere? Why do people need telephones? (Examination of the cause of an event and the repercussions of it, in 500 words)