What are ACTION verbs?

An action verb is a verb that describes an action, like run, jump, kick, eat, break, cry, smile, or think. 

 

When using action verbs, the sentence structure will be:
SUBJECT
--->
ACTION VERB
--->
 THE REST OF THE SENTENCE
(noun)
(verb)
(adjective, adverb, noun, complement, or nothing)
Here are some examples of action verbs in sentences.
Greg is kicking the ball now. The action verb is kicking.  It describes what Greg is doing.  
The wind blows constantly in Chicago. The action verb is blows.  It describes what the wind does.
He accepted my apology. The action verb is accepted.  It describes what 'he' did. 

What are LINKING verbs?  

A linking verb is a verb that links (connects) the subject of the sentence to information about that subject.   Linking verbs do not describe action. 
When using linking verbs, the sentence structure will be:
SUBJECT
--->
LINKING VERB
--->
 INFORMATION ABOUT THE SUBJECT 
(noun)
(verb)
(adjective, noun, or complement)

Some verbs are ALWAYS linking verbs because they never describe an action.  Other verbs can be linking verbs in some sentences and action verbs in other sentences.  

The following three verbs are ALWAYS linking verbs:  

to be (is, am, are, was, were, has been, have been, had been,  is being, are being, was being, will have been, etc.)
to become (become, becomes, became, has become, have become, had become, will become, will have become, etc.)
to seem (seemed, seeming, seems, has seemed, have seemed, had seemed, is seeming, are seeming, was seeming, were seeming, will seem)
Here are some examples of linking verbs that are ALWAYS linking verbs in sentences: 
 “The ball is red.” 'Is' is a linking verb that connects the subject, ball, to information about that subject (that it is red).
 “The children are smart.” 'Are' is a linking verb that connects the subject, children, to information about that subject (that they are smart).
 “The child will be tall five years from now.” 'Will be' is the linking verb connecting 'child' to the fact that he will be 'tall five years from now.'
“The cat seems fine.” 'Seems' links the subject, cat, with information about the cat (that it is fine).
 “The dog became thin after his surgery.”  'Became' links the subject, the dog, with information about him (that he became thin).

 

Verbs that can be both ACTION and LINKING verbs

There are verbs that can be linking verbs in SOME sentences, but are action verbs in other sentences.  One way to determine if the verb is functioning as an action verb or a linking verb is to substitute the word “is” for the verb in question. If the sentence still makes sense, then it is probably a linking verb.  If the sentence would not make sense with the word “is,” then it is probably an action verb in the sentence.
The following are examples of verbs that can be linking verbs in some sentences and action verbs in other sentences:
look smell appear 
prove sound feel
remain taste grow
Here are some sample sentences of verbs used as linking verbs and actions verbs. 
Used as Linking Verbs Explanation
Jane appeared uninjured after the accident.  You could substitute the word 'is,' for the word 'appears,' and the sentence would still make sense: "Jane is uninjured after the accident."  This lets you know that appeared is a linking verb in this sentence.
The cake smells good! This sentence describes the cake.  “Smells” is a linking verb in this sentence.  It connects the subject, cake, with information about that subject—it smells good.
The woman grew silent. This sentence may seem confusing.  Remember that the word “grow” has more than one meaning!  In this sentence, “grew” means BECAME.  The woman became silent.  
Used as Action Verbs Explanation
Before I could leave, Jane appeared. In this sentence, appeared is not linking anything.  It is telling the action that Jane did.  She appeared, or showed up.
Ellen smells the cake. The word, smells is not linking anything.  If you replaced smells with 'is' the sentence would not make sense.  That means smells must be an action verb in this sentence.  Ellen performed the action of smelling the cake.
The gardener grew some flowers.  The word, grew, is not linking two things together here.  If you tried to replace grew with 'is' the sentence would not make sense.  This means that grew must be an action verb.  The gardener performed the action of growing some flowers.