Both words have to do with impact, influence. The crucial difference between them is their word form which people tend to interchange. Affect is the verb and effect is the noun. Effect means a consequence or a result produced by a cause or an agency. It also refers to the power to produce results, moreover, it can also mean efficacy, force or validity. Although it is a noun, the verb form of the world also exists but the meaning is different. If it is a verb, in legal context, for example, it means to bring to pass, to execute, to enforce or to accomplish. As for affect, which is primarily a verb, means to have an influence, to act on the emotions. It might occur as a noun, in that case, affect refers to a feeling or an emotion which is manifested by facial expressions or body language.
