A quick and easy one today. Small but disproportionately annoying.
Effect is a noun (mostly) and means ‘result’. It’s something that is, or you have or give. There can be one or many. If you can count is, spell it with an ‘E’.
ONE EFFECT of bad grammar is that I become grouchy.
Affect is a verb (apart from very specific cases) and it means ‘to influence’. You can’t count it, because it is an action.
His ACTIONS AFFECTED me.
Whilst both can be used as nouns and verbs, the predominant use is as above.
As a verb, ‘to effect’ is used almost always in formal speech, such as journalism and means ‘to cause, to bring about a result’: The government spokesperson said the cutbacks were designed to effect economies in this sector.
As a noun, ‘affect’ is almost always used in psychological jargon, to comment on people’s moods and behaviour.