About "verb conjugation"

A verb consists of a stem and auxiliary verb / particle.
A stem of a verb should be changed depending on its meaning in the sentense.
Basically "verbs" have 6 forms of conjugation.

a : Imperfective form (mizenkei) : to be attached with ,for example, negative auxiliary "nai"
b : Continuative form(ren'youkei) : to be attached with, for example,polite auxiliary " masu"
c : Terminal form (shuushikei) : to be used at the end of the sentense.plain form. dictionary form
d : Attributive form (rentaikei) : to be attached with mainly a noun,for example, "toki"(when)
e : Hypothetical form (kateikei) : to be used for conditional foms with " reba/ eba".
f : Imperative form (meireikei) : to be used to make verbs be commands.

It is not important to know grammatical terms mentioned above, but when you learn a verb, you'd better see all the conjugation forms of the verb.

I give you an instance the case of "kaku"(:write)
form a :kaka(stem): kaka-nai : do not write
form b : kaki(stem):kaki-masu : write (polite)
form c : kaku(stem):kaku :write(plain)
form d : kaku(stem):kaku-toki : write,when : when you write
form e : kake (stem): kake-ba : write,if : if you write
form f : kake(stem): kake : write : (You) Write.

Sometimes we can see additional form g.
form g : kakou : let's write.

Moreover, in the case of past tense, "ta" / "da" / "ita"/"datta" and etc would be attaced to form b,but you should learn them as another form h.

e.g.
kaku :write
(kaka-nai, kaki-masu, kaku,kaku-toki,kake-ba,kake,kakou,kaita)
miru : look, see
(mi-nai,mi-masu,miru,miru-toki,mire-ba,miro,miyou,mita)
yomu : read
(yoma-nai,yomi-masu,yomu,yomu-toki,yome-ba,yome,yomou,yonda)
hashiru : run
(hashira-nai,hashiri-masu,hashiru,hashiru-toki,hashire-ba,hashire,hashirou,hashitta)