Lesson 1 / الدرس 1

What happens when you type an address / ماذا يحدث حين تكتب عنوانًا

You type an address and a page appears. Between those two moments a name is looked up, a connection is opened and encrypted, a request is sent, a response comes back, and a browser draws it. This course is that journey, one step at a time.

تكتب عنوانًا فتظهر صفحة. وبين هاتين اللحظتين يُبحث عن اسم، ويُفتح اتصال ويُشفَّر، ويُرسل طلب، وتعود استجابة، ويرسمها متصفح. وهذه الدورة هي تلك الرحلة، خطوة خطوة.

It feels instant. You type training.gt4it.com, press Enter, and the page is there. But a great deal happened in that second, across several machines, in a fixed order — and when a site is slow, or broken, or warns you it is "not secure", the reason is always one of those steps. Knowing them turns a mystery into a checklist.

يبدو الأمر فوريًا. تكتب training.gt4it.com وتضغط Enter فتظهر الصفحة. لكن الكثير حدث في تلك الثانية، عبر عدة أجهزة، بترتيب ثابت — وحين يكون موقع بطيئًا أو معطوبًا أو يحذّرك بأنه "غير آمن"، فالسبب دائمًا إحدى تلك الخطوات. ومعرفتها تحوّل اللغز إلى قائمة تحقق.

The whole journey, in seven steps

The address is read. The browser splits what you typed into its parts: which protocol, which computer, which page.
The name is looked up. training.gt4it.com is a name for people. The network needs a number, and DNS is what turns one into the other.
A connection is opened to that number, on a particular door — a port.
The connection is secured. Both sides agree on a secret nobody in between can read, and the server proves it is who it claims to be.
A request is sent. A few lines of text saying what you want and what you can accept.
A response comes back — a code saying how it went, some information about the answer, and the answer itself.
The browser builds the page from that answer, asking for every image, stylesheet and font it mentions — each one repeating steps 2 to 6.

<ol class="trip">
    <li>Read the address</li>
    <li>Look up the name</li>
    <li>Open a connection</li>
</ol>

Run this to see the journey as a list you can look at while you read the rest of the course. Every lesson from here takes one of these steps and opens it up.

The two words everything rests on

Two words are worth fixing now, because everything else rests on them. The client is whatever asks — usually your browser. The server is whatever answers. They are roles, not machines: a computer can be a server for one conversation and a client in the next, and often is.

Step	Answers	Lesson
Read the address	What am I asking for?	3
Look up the name	Which machine has it?	4–6
Open and secure	Can I trust this connection?	12–13
Request and response	What did I ask, what came back?	7–11
Build the page	Why does it look like that?	15–17
Where it all lives	Whose computer is it on?	18–20

The journey, and where in this course each step is opened up.

Try it live / جرّب بنفسك

<h1>One page load</h1>

<ol>
    <li>Read the address — <em>what could go wrong?</em></li>
    <li>…</li>
</ol>

Preview / المعاينة

Check yourself / اختبر نفسك

1. What is a "client" in this course?

2. Why does typing one address usually cause many requests?

3. Which step turns a name like gt4it.com into something the network can route to?

أي خطوة تحوّل اسمًا مثل gt4it.com إلى شيء تستطيع الشبكة توجيهه؟

Your task / مهمتك

Write the seven steps out in your own words as an ordered list, and beside each one name a thing that could go wrong at that step. You are building the checklist you will use every time a site misbehaves.

اكتب الخطوات السبع بكلماتك في قائمة مرتبة، وسمِّ بجانب كل واحدة شيئًا يمكن أن يخطئ عندها. فأنت تبني قائمة التحقق التي ستستخدمها كلما أساء موقع التصرف.

All seven steps appear, in order الخطوات السبع كلها موجودة، بالترتيب
Each step names something that could fail there كل خطوة تسمّي شيئًا يمكن أن يفشل عندها
It is written in your own words, not copied مكتوبة بكلماتك، لا منسوخة