What is the difference between HTTP/1.1 and HTTP/2?

HTTP/1.1 and HTTP/2 are different versions of the HTTP protocol. The main difference between them is in speed, efficiency, and the way data is transferred.

In short: HTTP/2 is faster and smarter than HTTP/1.1, but the underlying logic (request → response) is the same in both.

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#The main difference in simple terms

• HTTP/1.1 Works "in turn": one request first → then the next
• HTTP/2 Works "in parallel": many requests and responses at once over a single connection

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#HTTP/1.1, how it works

Features of HTTP/1.1:

• one request, one response
• requests are processed sequentially
• the browser opens several connections to the server to speed things up
• headers are sent as text and are often repeated

#The problem:

If one request is slow, the rest wait their turn (this is called head-of-line blocking).

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#HTTP/2, what changed

HTTP/2 was created to solve HTTP/1.1's problems.

#Main improvements:

#1. Multiplexing

• many requests and responses
• at the same time
• over a single TCP connection

Nothing gets blocked or has to wait in line.

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#2. Binary protocol

• HTTP/2 transfers data in binary format
• instead of as text

It is processed faster by computers.

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#3. Header compression

• headers are not repeated every time
• they are sent in compressed form

Less traffic, faster loading.

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#4. Server push (optional)

• the server can send resources on its own
• without waiting for a request

For example:

• HTML → the server immediately sends CSS and JS

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#What did NOT change

Important for an interview:

• the HTTP methods stayed the same (GET, POST, and so on)
• the response codes are the same (200, 404, 500)
• the URL and API logic do not change
• for an API developer, there is almost no difference

What changes is the transport, not the meaning of HTTP.

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#Short comparison

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#Short answer for an interview

Remember this wording:

HTTP/2 differs from HTTP/1.1 in that it supports multiplexing, a binary data format, and header compression, which allows several requests and responses to be transferred at once over a single connection and significantly improves performance