Verbs are special words which describe action. Nothing would ever get
done if it were not for verbs. Look at a sentence on your screen or
on paper -- it just lies there listless, a mere collection of random words
until a verb comes to infuse it with life.            

                    Consistency of Tense and Pronoun Reference    

Basic form is the form in which verbs are listed in the dictionary.  It is used for present tense
                  for all subjects except third-person singular subjects.  This is the form with "to" in front of it.
                  It is called the "infinitive" form of the verb.
Example:  to walk  to trade

Past Tense Form of most verbs is constructed by adding –ed or –d to the basic form.
Example:  I walked.  You   traded.
(there are multiple irregular constructions which cannot be listed here.)

The present participle is the –ing form of a verb.  This form is used with the helping verbs
                      am, is, are, was, or were to denote continuing or ongoing action.  (also called a gerund) 
Example:  I am walking.  You are trading.

The past participle of a verb is usually the same as its past tense form.  This form is used with
                               have, has, had, am, is, are, was, or were as helping verbs .
Example:  I have walked.  You have traded. 

             Verbs in the

  Present tense: express present action or habitual (repeated) action.
  Example:  I walk.  You trade.

  Past tense:  express actions that took place in the past.
                    {formed by adding -ed or –d to the end of the basic verb form}
  Example:  I walked. You traded.    (or a variety of irregular verb constructions)

  Future tense:  describe future actions.   {formed by adding will or shall to the basic form.}
  Example:  I will walk.  You shall trade.

  Present Perfect tense:  describes an action that began in the past and either has been finished
                                     or is continuing at the present time. {made by adding the correct form
                                     of the helping verb have to the past participle of a verb.}
  Example:  I have walked.  You have traded.

 Past Perfect tense:  describe an action that was completed in the past before another past action.   
                    {formed by adding had to the past participle of a verb.}
 Example:  I had walked.  You had traded.

 Future Perfect tense:  describe an action that will be completed before some time in the future. 
                                      {is formed by adding will have to the past participle of a verb.}
 Example:  I will have walked  You will have traded.  

    

 

  The Present Progressive Tense expresses an action taking place at this moment or
                                              that will occur sometime in the future and is formed by
                       adding the correct present tense form of the helping verb be to the -ing form of the verb. (the gerund)
  Example:  I am walking.  You are trading.      

  The Past Progressive Tense expresses and action that was in progress at a certain time in the past
                    and is formed by adding the correct past tense form of be to the -ing form of the verb.
  Example:  I was walking.  You were trading.

  The Future Progressive Tense expresses an action that will be in progress at a certain time in the future
                    and is formed by adding will be to the –ing form of the verb.       
  Example:  I will be walking.  You will be trading.