What is the general algorithm of a version control system?

Question

git

The question is not really about git and svn. I want to make a service based on custom editing of the same text. But I can not delve into the algorithm of work. The problem is that if the participants work on the same site, then the last change that was made wins out?
For example, I can suggest taking Wikipedia or notabenoyd.

Answer 1

The change that the user chose when merging wins. For example:
There is a string: ABCD
1 change: ACBD
2 change: ACBE
3 change: DCBA
The string consists of characters:
A -> D
B -> C
C -> B
D -> E -> A
The first three characters have the same final change , so they will certainly be accepted
And the latter needs the user who performs the merge to select E or A
That is, either the end result:
DCBE
DCBA