AFFECT - EFFECT

Many people are confused about the difference between affect and effect.
Before going any further, remember that “affect” is almost always a verb, 
whereas “effect” is more commonly used as a noun.

Affect and effect are used as follows : 

• AFFECT :
  Affect is most often used as a verb meaning ‘to have an impact’, ‘to change’ or 'to alter'.
  
  • Nutrition affects our health.
  • His attitude affected the atmosphere in the office.
  • Severe flooding affected many regions.
  • The snow storm affected air traffic.
  • Public protests did not affect the government's decision.
  Affect also has another, less-used, meaning: ‘to put on a false show of’ or 'to pretend':
  • She affected indifference although she was very upset.
    (= she pretended that she did not care)

• EFFECT :
  Effect is most often used as a noun meaning ‘a result’, ‘a consequence’ or ‘an influence’.
  The expression ‘have an effect on’ is often used.
  
  • His words produced the desired effect.
  • Her warning had no effect on the children.
  • The effect on the economy was disastrous.
  • The medication will not have an immediate effect.
  • Music often has a soothing effect on people.
  Effect can also be used as a verb meaning ‘to bring about’, ‘to make something happen'
  or 'to put into operation'.  The use of effect as a verb is usually found in formal contexts.
  • The firm effected the transition to computerized accounting last month.
  • The bank was requested to effect the transfer of funds immediately.
  Effects [plural] can also mean 'personal property or possessions'.
  •  Personal effects should be packed separately.

In most everyday contexts it is safe to remember that 'to affect' =  'to have an effect on'.
Affect is related to action whereas effect is related to consequence or result.