What Is HTTP/2? Everything You Need to Know for SEO

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You might even see HTTP/2 come up in your Google Lighthouse audit report, both inexperienced (In Use) or as a possibility to enhance web page load velocity.

But what precisely is it and how will you use HTTP/2 for SEO?

In this information, you’ll study what it’s and the way it works, the professionals and cons of HTTP/2, and the way to implement it to assist attain your web page velocity targets.

What is HTTP/2?

HTTP/2 is a protocol for governing the communication between a browser making a request and the server that comprises the requested data.

It was formally standardized in 2015 and is preceded by HTTP/1, which has served the online for over 15 years.

Google confirmed that they might begin crawling websites over HTTP/2 in November 2020 and John Mueller confirmed in May 2021 that they’re already crawling over half of all URLs with the HTTP/2 protocol.

He stated on the time that, “this means Googlebot won’t need to spend as much time crawling your server as before.”


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What Is a Protocol?

A protocol is basically the algorithm in place to handle the request between purchasers and servers. It sometimes consists of three foremost components: the Header, Payload, and Footer.

The Header comprises data together with the supply and vacation spot deal with of the web page, in addition to dimension and sort particulars.

The Payload is the precise data that will likely be transmitted.

This is adopted by the Footer, which routes the request to the supposed recipient and ensures the info is freed from errors when transmitted to the browser.

How Does HTTP/2 Work Differently from HTTP/1?

My favourite method to perceive HTTP requests is Tom Anthony’s truck analogy.

Basically, a truck represents the request from the consumer to the server, and the street the truck travels alongside is the community connection.

Once the truck carrying the request from the browser reaches the server, it’s going to load the response and carry it again to the browser.

HTTPS provides a layer of safety to these responses, to guarantee nobody is in a position to look within the truck to see what it comprises, for instance, private knowledge or delicate data.


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The foremost problem right here is that the vans making the request can not journey sooner than the velocity of sunshine. They should additionally journey at a constant velocity, no matter how huge the request is and the way far they’ve to journey to get to it.

Another factor to think about is that almost all web sites require a sequence of many requests and responses so as to load one web page. For instance, picture information, CSS, and/or JavaScript information might also have their very own dependencies, which require extra journeys to be made between the browser and server.

When making requests through HTTP/1, every truck wants its personal street, or community request, and new community requests additionally want to be made for sure requests. This all provides to the latency.

Typically, solely six simultaneous connections might be made at one time, main to different requests being compelled to wait for community connections to be free. Waterfall diagrams are a helpful method of seeing this latency in motion.

Enter HTTP/2

This is the place HTTP/2 can be utilized to present a optimistic impression on request behaviors.

In addition, the Multiplex characteristic signifies that extra vans can run on a single street at one time, so the community connection is in a position to deal with extra requests and ship extra responses sooner.

The contents of those requests and responses keep the identical; they’re simply dealt with in a barely completely different method.

Another helpful characteristic of HTTP/2 is Server Push, which signifies that the server is in a position to reply to a request with a number of responses without delay.

So say for instance we want to return CSS and JavaScript information along with the HTML; these can all be despatched on the similar time, relatively than needing to be individually delivered to the browser.

HTTP/2 Tech Features

HTTP/2 is constructed on the identical syntax as HTTP/1, which implies the protocol is extra a refresh than a full migration. This was a deliberate determination so as to make the transition as seamless as potential.


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The key options of HTTP/2 embody:

Binary Not Textual

HTTP/2 introduces a change to the reworking protocol, from textual content to binary to full the request to response cycles. The similar duties will likely be executed, simply utilizing binary instructions — 1s and 0s, relatively than textual content.

This was carried out to simplify the implementations of instructions and means they’re simpler to generate and parse.


Multiplexing permits a number of requests to be made without delay over a single connection. This will break the payload into smaller sequences, parse and transmit them over a single connection, then reassemble them earlier than they attain the browser.

The foremost intention of this modification was to deal with points with resource-consuming requests and assist to stop requests and responses from blocking others.

Header Compression

Header compression is designed to scale back the overhead that comes with the slow-start mechanism in HTTP/1.

As most web sites are wealthy in graphics and content material, consumer requests trigger a number of near-identical header frames to be despatched again to the browser which may trigger latency and pointless consumption of already restricted community assets.


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The header compression mechanism supplies the power to compress massive numbers of redundant header frames and permits the server to preserve a listing of headers utilized in earlier requests. Essentially the headers will likely be encoded in a single compressed block and despatched to the consumer collectively.

Server Push

This permits assets which can be doubtless to be used to be pushed right into a browser’s cache earlier than they’re requested. Information or assets which can be anticipated to be in future requests (based mostly on earlier requests) will likely be despatched alongside, too, relatively than ready for one other consumer response for it.

This prevents the necessity for one other request and response spherical journey and is designed to scale back the community latency that comes with a number of assets getting used to load a web page.

Stream Prioritization

Stream prioritization is the place desire is given to explicit knowledge streams, based mostly on the dependencies and weight which can be assigned to every.

This permits the server to optimize useful resource allocation based mostly on the necessities of the end-user.


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Support for HTTP/2 is simply obtainable by way of encrypted connections, which implies it requires HTTPS. Unsurprisingly, the 2 complement one another in some ways.

Not solely does it enhance safety for customers and functions, but it surely additionally requires fewer TLS handshakes and leads to decrease consumption of assets on each the consumer and server-side.

Pros of HTTP/2

Naturally, as up to date expertise, HTTP/2 does carry some advantages.

Updating to HTTP/2 shouldn’t be a migration and would require no change in URLs. It is a protocol change that won’t require an excessive amount of effort from the SEO aspect.

I’ve explored 4 of the largest advantages from an SEO perspective beneath, nevertheless, this checklist shouldn’t be exhaustive to the general benefits of HTTP/2.

Web Performance

Several of the brand new options in HTTP/2 have been designed to enhance the efficiency of internet sites and to assist save assets wanted to crawl web sites.

For instance, multiplexing signifies that requests and responses is not going to block one another which helps to scale back latency and in flip present a sooner internet efficiency.


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The potential to ship and obtain extra knowledge per communication request is one other sensible instance of efficiency benefits.

In addition, stream prioritization permits efficient useful resource utilization which reduces the time taken to ship content material requests to the person.

Mobile Performance

In addition to general internet efficiency, cell efficiency will also be improved thanks to HTTP/2. This is as a result of it’s designed within the context of present-day utilization developments, which cell positively is.

Multiplexing and header compression notably assist with lowering latency in accessing internet pages, and that is additionally seen throughout cell networks which can have restricted bandwidth.

Essentially, HTTP/2 optimized internet expertise for cell customers in ways in which have been beforehand attributed solely to desktop customers, together with by way of efficiency and safety.

Improved User Experience

Due to the above-mentioned efficiency enhancements, person expertise can also be going to be positively affected by HTTP/2. It’s no secret {that a} fast-loading web site leads to elevated buyer satisfaction and general model favor.

As Google says, there’s a 32% enhance in bounce price likelihood if a web page load goes from 1 second to 3 seconds, and HTTP/2 is only one method you possibly can assist to enhance load velocity.


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Increased Security

Due to HTTP/2 needing to be served over HTTPS, it’s going to guarantee all web sites are encrypted and secured.

In addition, it additionally helps to be certain the functions themselves are shielded from any malicious assaults which might outcome within the web site being served handbook penalties or doubtlessly being dropped from search outcomes altogether.

Advantages for SEO

Of course, all of those mixed may have a optimistic impression on SEO, too.

While Google has confirmed that being on HTTP/2 is not going to present a direct rating enhance, not directly these elements will feed into the upcoming Page Experience replace particularly.

They can even all impression a web site’s visibility in search, along with person expertise and conversions.

Cons of HTTP/2

As with all applied sciences, HTTP/2 additionally brings some cons for you to think about.

One unfavorable is that not all browsers help HTTP/2. It’s price noting that by the tip of 2015, most main browsers added help for the brand new protocol; nevertheless, it’s price making certain the browsers your customers entry the location on are supported.


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Caniuse.com reveals which browsers help HTTP/2 and on the time of writing, there are 9 older browser variations that don’t at the moment help it. However, international utilization of those browsers is low.

HTTP2 Browser Support.

HTTP2 Browser Support.

Due to the server push characteristic, there’s the potential for wasted bandwidth due to knowledge which may be despatched to the browser however not really used.

Just as a result of a request to load a web page may have a specific asset, or it might be anticipated that one other request will likely be made, it doesn’t all the time imply that it’s going to. This signifies that pointless assets could also be despatched to the browser.


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Also, as multiplexing could cause the server to obtain quick bursts of a lot of requests without delay, this has the potential to overwhelm servers, notably if they don’t seem to be throttled. There might also be minor delays and problems in debugging, due to the binary format getting used as an alternative of the textual content format utilized in HTTP/1.

Implementing HTTP/2

Upgrading to HTTP/2 in the end is determined by your server. If you aren’t at the moment in a position to help HTTP/2, converse to your server administrator or internet hosting supplier.

If your server is in a position to help HTTP/2, it might robotically serve content material over the brand new protocol. You can guarantee your server is in a position to help it by making certain you utilize a CDN that additionally helps HTTP/2 and that you’ve an up-to-date HTTPS certificates.

You can take a look at in case your server is in a position to help HTTP/2 through the use of the location http2.professional. This will inform you in case your server helps HTTP/2, ALPN, and Server-push.

HTTP2 Pro Server Support.

HTTP2 Pro Server Support.

In addition, you possibly can verify which assets are at the moment served over HTTP/2 inside Chrome Dev Tools.

Chrome Dev Tools Protocol.

Chrome Dev Tools Protocol.

Reload the web page and assessment the lists of requests made for the web page to load, inside the protocol column you will note which assets have been returned by way of HTTP/2. Google references this as h2.

HTTP2 in Network.

HTTP2 in Network.

It is price noting that you may’t ‘force’ Googlebot to crawl your web site over HTTP/2.


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If your web site helps it, then it’s eligible to be crawled with the protocol. But for the time being, Google will solely do that in the event that they deem it will be useful (resource-saving).

A Google Lighthouse audit can even show in case your web site is being loaded utilizing HTTP/2.

Lighthouse HTTP2.

Lighthouse HTTP2.

If your web site shouldn’t be but utilizing HTTP/2, it’s going to doubtless be added as a advisable alternative.

HTTP/2 recommendation.

HTTP/2 recommendation.

If you’re inquisitive about studying extra about HTTP/2, I extremely advocate studying the Google Developer Documentation, in addition to these HTTP2 FAQs.


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More Resources:

Image Credits

All screenshots taken by creator, June 2021

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