One describes how you feel, the other describes what causes that feeling.
"Bored" describes how a person feels: uninterested or restless with nothing engaging to do. It describes the state of the person suffering from boredom.
I was so bored during the class.
The kids are bored and want to play.
She gets bored easily.
"Boring" describes the cause of boredom: something that does not stimulate or interest you. A dull film is "boring"; the person watching it may be "bored".
That lecture was really boring.
He is the most boring speaker I have ever heard.
I find horror movies boring, not scary.
Common mistake
Trick to remember it
The person who feels something uses "-ed" (bored, tired, interested, excited). The thing causing the feeling uses "-ing" (boring, tiring, interesting, exciting). Person = -ed. Thing = -ing.
Quick rule
Did you know?
This -ed/-ing pattern applies to dozens of emotional adjectives: interested/interesting, excited/exciting, tired/tiring, amazed/amazing, confused/confusing, surprised/surprising, terrified/terrifying, fascinated/fascinating. Learn the pattern once and you unlock them all. It is one of the most regular and productive systems in English grammar, a single rule that multiplies your vocabulary instantly.
Exercise 1 · Pick the right one
The class was so _____ that half the students fell asleep.
Exercise 2 · Pick the right one
I was so _____ at the party. Nobody talked to me all evening.
Exercise 3 · Form the word
One describes something enjoyable, the other describes something that makes you laugh.
'A' is used before consonant sounds; 'an' is used before vowel sounds.
'A lot of' works for countable and uncountable; 'many' only for countable; 'much' only for uncountable.
'According to' cites an external source; 'based on' indicates the evidence behind a claim.
Bryan López
Founder of SpeakUP Academy