Here is a quick lesson in English grammar. I have often seen people make mistakes with the usage of the words affect and effect. I have even seen mistakes in websites and official documents, and so thought of clarifying the difference here.
Lets examine the difference. Consider these 4 sentences.
1. The settings in the device manager in the computer, effect the performance of the system. 2. The criminal act effected a significant change in the law and order situation in the county. 3. Soil erosion by water and wind affects the natural environment. 4. The affect of soil erosion can be seen in the the grand canyon.
Which of these are right / wrong? . ... ..... ... .
And here are the answers: (1 - Wrong, 2 - Right, 3 - Right, 4 - Wrong)
Here is how the difference can be understood.
When the word AFFECT is used in a sentence, the sentence also says "what" is being affected. The keyword here is "what". The word AFFECT always refers to the influence of a certain event ON SOMETHING. Hence, whenever we talk about affect, it always refers to a person, or thing, or similar.
In contrast, the word EFFECT is used in a sentence to indicate an action. The word EFFECT is used to describe "how" something was AFFECTED. The EFFECT of a certain event is another event. The word EFFECT indicates a result (remember cause-and-effect). This is different from AFFECT which refers to an object.
Lets look at the 4 sentences again.
In sentence 1, the sentence doesn't say anything about "how" the settings influence the performance. It only says that the settings influence the performance. So, the performance of the system is the object. Hence, the word to be used is AFFECT.
In sentence 2, the sentence refers to "change" in the law and order, which indicates action. The sentence is about the "influence" of the act on the law and order situation. Hence the word is EFFECT. The same sentence can be re-framed using the word AFFECT as, "The criminal act affected the law and order in the county by a significant amount."
In sentence 3, natural environment is the object of the sentence. Hence AFFECT. Hence correct usage.
In sentence 4, the sentence is referring to the influence of soil erosion. Hence the word is EFFECT.