Linguists often consider endings when determining the number of tenses in a language.
The English verb can only take two forms from the viewpoint of tense endings: present: talk
s and past: talk
ed.
The future is formed by adding an extra verb (the modal verb
will) in front of the verb -- not by changing an ending.
For this reason some textbooks use different terminology for English
verb tenses depending whether the verb form is made with endings or
with other verbs.
On this forum you will find all sorts of terminology. Some
of it conforms to the practice I just described, but much of it does
not.
CJ