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Hello, yes, students in this lesson will talk about version control systems, we are going to discuss

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why do we need them?

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I will give you the list of the most popular version, control systems.

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And we will focus our attention on get why we have to learn it.

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And at the end of this lesson, I will give you a short overview of good features and how it operates.

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First of all, get the same as ours and mission control systems is not a programming language.

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You might be wondering then why do we need to learn it?

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It is pretty common that multiple software engineers work on the same program simultaneously or different

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versions of a program are deployed on different environments.

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Thus, GM needs to have some tools that will allow them to track changes in the source code, configuration

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files and time documentation.

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For example, each engineer may have archive was the source code and after that key members have to

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merge got somehow together.

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While this approach might work, it is extremely inefficient and doesn't allow to track changes closely

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also for the purpose of finding localising and fixing the defect in the code.

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It is critically important to compare different versions of the code to identify where exactly back

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appeared to fix it.

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That's why we are, as a programmers should know how to use version control systems.

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Let's quickly discuss what is the most popular version control systems are.

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They are Baza CBS Marcorelle Subversion Get and according to this survey, get this used by almost millions

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of people who took part in this survey.

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Definitely get the most powerful and popular version control system nowadays.

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That is the first reason why we are going to learn it.

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The second reason is the fact that knowing how it works, it would be like piece of cake for you to

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understand how, as a controlled version, systems work.

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Every job description for software engineer require from your knowledge of it because of its popularity.

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As you might already understand, it is a program which is used to track changes in the source code

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during the development, but it can be used with any type of files.

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Right now we'll do high level overview of the gate.

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I will tell you key features and basic principles of how it operates.

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The key difference between the gate and other version control systems is that it doesn't store differences

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in files.

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It stores links to the snapshot of changed files in case file wasn't changed.

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Get doesn't store this file again.

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Instead, it stores just a link to the previous identical files that was already stored.

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So each time you can make changes, it takes a picture of what all files look like at the moment and

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stores a reference to that snapshot.

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This is important distinction between GIT and other version control systems.

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And another important get feature is the fact that you can't do anything without knowing this before

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snapshot of your file system is created, everything is check samed and hashas created afterwards.

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You can use this checksum to refer to this exact state of the files.

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That means it is impossible to change the contents of any file or directory without knowing about it.

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So each your command has 40 characters string composed of hexadecimal characters and calculated based

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on the contents of a file or directories structure.

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Hash looks like this and you can use this hash string to navigate between different versions of your

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code version.

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Control systems might be centralized and distributed in centralized.

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All engineers are connected to the main server and all people collaborate through that server.

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The biggest drawback here is the fact that when central server is down, you can't collaborate in distributed

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version control systems.

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Each engineer has a copy of the whole project and can easily restore it if needed or in case there is

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no network get is a distributed version control system to perform most of operations.

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And yet you don't need information from another computer.

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That's why there is no latency overhead.

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When you work with Target, you have entire history of your repository of all changes right on your

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local computer.

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You have hidden dot gate folder that contains all information about the repository and you don't necessarily

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need Internet connection to perform some operations was get if you are in airplane and you want to do

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some coding, you can do that and successfully save all your changes.

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You can also navigate the.

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In the repository of your project and navigate to different versions of your code while being offline,

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for example, in simple version and CVS, you can edit files, but you can't save changes to database

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just because you are offline.

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It doesn't seem to be a huge problem, though, but probably in the real world you want love this.

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Having all repository history on your local computer gives you instant access for all changes.

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That also means much better performance.

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Before we get deeper to get program and get comments, I want you to understand basic principle of interaction

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with Get This will help you to understand our next lessons.

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All your files, according to it, can be in three different states.

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Modify it.

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That means you modified the file, but you have not committed your changes yet.

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Staged.

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This means you have marked a modified file to be present in the next snapshot of your file system.

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Information about such changes is placed in the file with name index.

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That's why during the course, sometimes I'm going to say at file to stage or at the index, and you

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will understand that this means the same across all files from staging area that are marked to be present

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in the next snapshot are reflected in index file.

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Does it make sense?

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And the state is committed.

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This means that data is safely stored in your local database.

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We can say that you have working directly that a set of files you work with the staging area is the

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index file and Hidden doGet folder is a folder where it stores all data about your project, including

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database for your project.

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So your basic interactions with GIT are going to look like this.

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You changes do file or to a set of files.

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You add those files to index, you can make the changes and you create a snapshot of your files.

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That said, let's recap what we have learned today.

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Today we learned why we need version control systems.

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Now, you know, the most popular version, control systems.

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And you know, that git is the most popular v.c as you learn the key features of the kit and understood

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how it operates, I believe now we are ready to proceed with our next lesson.

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Thanks a lot for your attention and see you in the next lesson.