The difference between affect and effect primarily lies in their grammatical roles and meanings:

• Affect is most commonly used as a verb , meaning to influence or produce a change in something or someone. For example, "The cold weather affected the crops" means the weather caused a change in the crops

• Effect is most commonly used as a noun , meaning the result or consequence of a change. For example, "The effect of the cold weather was damaged crops" means the damaged crops are the outcome of the weather's influence

A simple way to remember this is:

• A ffect = A ction (verb)
• E ffect = E nd result (noun)

There are some less common uses:

• Affect can also be a noun in psychology, referring to a visible emotional expression (e.g., "He showed a joyful affect")

• Effect can sometimes be used as a verb meaning to bring about or cause something to happen (e.g., "The new law effected changes"), but this is rare

In summary:

• Use affect when describing the action of influencing or changing something.
• Use effect when referring to the outcome or result of that action.

Example:

• "The rain affected the plants." (verb)
• "One effect of rain is faster plant growth." (noun)

This distinction covers the vast majority of cases and helps avoid confusion.