What happens when you type google.com into your browser and press enter? (Detailed Analysis)

In this video I want to go through what really happens under the hood when you type google.com and you hit enter in a browser. This is inspired by alex’s github page below, it is a great detailed description of what happens. I did however add more details to certain areas and I removed some stuff like keyboard events and low level operating system like that. So if you are interested stay tuned! Alex Github page https://github.com/alex/what-happens-when Chapters 0:00 Intro 1:54 Initial Typing 3:00 URL Parsing 7:40 DNS Lookup 19:15 TCP Connection 24:19 TLS, ALPN. SNI 33:38 First GET request 40:00 HTML Parsing initial Typing As you type g the browser will attempt a search and display an auto complete result of the previously visited sites Some browser does an actual search using the default configured search engine we will skip that part. This will have he same effect as next steps URL PARSE As you complete the phrase google.com and hit enter , the browser will parse and will figure out whether this is a url or a search term . It is a url so it will attempt to visit the website google.com HTTP or HTTPS? Determine the port The next step is to determine which protocol to use HTTP or HTTPS? to know that there is a protocol called HSTS list and we made a video about that tech. It is a local list of websites that only need to communicate with HTTPS. Google.com is in the HSTS list so we will use HTTPS so we now know the port is 443! We need to figure out the IP address so we can establish the connection DNS Lookup TO find out the IP address we do a DNS look up .first we ask the operating system, because the domain could be cached, we find that its not . The OS then looks through the hosts file and see if there is a n hardcoded entry , there isnt .. Next the browser check if DoH is enabled DNS over HTTPS if yes then it communicate with the DNS provided (e.g cloud flair and ask for DNS) thats another TLS connection assume we are not using DoH The we est