What does git fetch do exactly?

Question

Edit: I checked this. What does FETCH_HEAD in Git mean? before asking a question.
Sorry for the original inaccurate question.

My question is: how does fetch work? Does the extraction retrieve the entire current log?

This is my situation: my teammates and I use the same repository, which has only one branch. Therefore, we need to make a selection before clicking anything.
Usually we do it as follows:

git status
git add .
git commit -m message1
git fetch origin
git reset head
git status
git add .
git commit -m message
git push

But after reset it seems that my previous commit (c message1) was gone.

Is this normal or is something wrong?
How can I access my local history? They are synchronized, but my local history is gone.

, : CLI Git.
- "git fetch head", .
, ? ?
"git fetch" "git fetch head"?

Answer 1

git fetch . .

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A <-B <-C   <-- master (HEAD)

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A <-B <-C <-D   <-- master (HEAD)

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A--B--C--D   <-- master (HEAD)

: git fetch

git fetch, Gits, , . , Git, , :

A--B--C

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Git commit D. - - , . , . () ; "Sally" . : :

A--B--C   <-- sally/master
       \
        D   <-- master (HEAD)

, . :

A--B--C--E--F   <-- master (HEAD)

, ( , git fetch):

A--B--C   <-- harry/master
       \
        E--F   <-- master (HEAD)

git fetch, Git Sally Git , - , master C. - E F. , Git , . Git , :

        E--F   <-- sally/master
       /
A--B--C
       \
        D   <-- master (HEAD)

, git fetch , .

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rebase- git reset, ,

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       \
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A--B--C--D---G   <-- master (HEAD)
       \    /
        E--F   <-- origin/master

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git rebase , , , . , commit D F, G, , git rebase , , , , .

origin/master, , , D. git rebase D, D', F, D' F. : ⁵

A--B--C--D   <-- master
       \
        E--F   <-- origin/master
            \
             D'   <-- HEAD

, git merge , commit D. ⁴ , , , , master, commit D':

A--B--C--D   [abandoned]
       \
        E--F   <-- origin/master
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             D'   <-- master (HEAD)

D. ⁶ , , :

A--B--C--E--F   <-- origin/master
             \
              D'   <-- master (HEAD)

git push commit D' origin.

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git pull git fetch,

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Answer 2

, git fetch - .

 --o--o--o (origin/master)
          \
           x--x (master: my local commits)

, , git fetch:

git fetch

--o--o--o--O--O (origin/master updated)
         \
          x--x (master)

git rebase origin/master

--o--o--o--O--O (origin/master updated)
               \
                x'--x' (master rebased)

git push

--o--o--o--O--O--x'--x' (origin/master, master)

, Git 2.6, :

git config pull.rebase true
git config rebase.autoStash true

git pull origin/master. git push.