Glossary

 

Asynchronous JavaScript and XML.
A JavaScrip-based method for dynamically requesting resources or processing activities on a server without the requirement of a full reload of the current web page.

 

 

Accelerated Mobile Pages.
A Google-initiated open source project providing a framework for building content pages that loads fast. Google no longer include AMP pages in thier ranking algorithms consequently their popularity is diminishing.

 

 

Benchmark.
A point of reference that may be compared or assessed. It is used to measure and evaluate performance, quality, or progress..

 

 

Content Delivery Network.
Benefits website visitors by establisshing interconnected servers that are distributed across the globe so that data can be served from a local point of presence (POP) and cached to reduce access times for future requests. The key benefits are faster more secure and reliable delivery to client requests.

 

 

Cross-Origin Resource Sharing.
A method of determining browser behavior when requesting resources from a different server (cross-origin). The method consists of tranmitting HTTP headers to a server to validate if a request for access is permitted or blocked. The criteria is defined in the target server's resource sharing policy.

 

 

Carbon dioxide equivalent.
The collective term for combining the different greenhouse gases, such as, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O) and ozon,e together under the banner of a single metric.

 

 

Critical Render Path.
The primary processing steps taken by a browser to combine the web artifacts of a web page to initiate the compositing of pixels (rendering) in the browser. Use the link to gain further understanding of the Critical Render Path.

 

 

Chrome User Experience Report.
The dataset that collates real-user experiuence as captured and reported by the Google Chrome browser. The dataset contains all of the Core Web Vitals metrics.

 

 

Cumulative Layout Shift
A measurement of visual stability. Observed by tracking the amount of unexpected layout shifts that occur during page loading. It is recommended to be 0.1 or below.

 

 

Core Web Vitals
Core Web Vitals are essential metrics within the broader Web Vitals framework that are relevant to every web page. Each metric highlights a unique aspect of the user experience. These are it's loading, interactivity, and visual stability.

 

 

Domain Name System.
The Domain Name System is an internet service that translates a named computer, service, or other internet resource into an IP address so that it can be identified as a specific node on the internet. Effectively it is the internet's address book. Established by the IETF in RFC 1035 a further understanding can be found at What is DNS?.

 

 

Greenhouse gases
Greenhouse gases. (GHGs) are gases in the earth's atmosphere that trap heat.

 

 

grams of Carbon Dioxide equivalent.
grams of Carbon Dioxide equivalent emissions is used to group all GHG emissions under a single metric.

 

 

Green Host.
A green host is a web hosting provider that minimizes environmental impact by using renewable energy, offsetting carbon emissions, and implementing eco-friendly infrastructure to power websites sustainably and reduce the digital carbon footprint.

 

 

HTTP Archive.
A permanent repository of web performance information such as size of pages, failed requests, and technologies utilized. The information enables trends in how the Web is built to be observed and provides a common data set from which to conduct web performance research. The information is collected and made available free of charge. Investigate the archive at HTTP Archive.

 

 

HyperText Transfer Protocol.
An application layer protocol within the open systems interconnection (OSI) model that breaks the flow of data into a series of small packets. The packets are exchanged between the web server(s) and end-user devices using a transmission protocol such as TCP or UDP. The packets are then reconstructed by the browser or User Agent on the end-user device. The full specification and documentation for HTTP is managed by the IETF HTTP Working Group.

 

 

HyperText Transfer Protocol Secure.
An encrypted and secure version of HTTP. Encrption is achieved by prepocessing the HTTP stream using TLS prior to transmission. It is then decrypted on the target device. Further detail is available at What is HTTPS?.

 

 

Internet Assigned Numbers Authority.
Provides global coordination of DNS Root, IP addressing, and other Internet protocol resources. Learn more about the IANA at https://iana.org.

 

 

Internet Engineering Task Force.
The de-facto arbiter for internet standards. All developed standards are voluntary and are generally adopted by Internet users, network operators, and equipment vendors. The IETF has no enforcement powers over the internet, it's development or it's use but the adoption of it's standards enables the internet to be evolve with interoperable devices and services. Learn more about the IETF at https://ietf.org for further information.

 

 

Interaction to Next Paint.
The measurement of interactivity. By calculating the time from when a user interacts with the web page to when the next frame is painted on the screen. The recommended value is 200 milliseconds or less.

 

 

International Organization for Standardization.
An independent, international and non-governmental organization that brings experts from across the globe together to agree and document the best ways of doing things. These agreements may eventually become internationally recognised standards. Visit https://www.iso.org for further information.

 

 

Internet Service Provider.
An organisation that delivers connection to the internet for customers for the delivery of internet services, such as web browsing, email, data stoirage and cloud services.

 

 

Latency
Measured in milliseconds it is the sum of the time taken for a request from the originating device to traverse the network to the requested server added to the time for the return trip back to the originating device. Latency is also known as RTT.

 

 

Largest Contentful Paint
A measure of loading performance. A calculation of the time it takes for the largest content element such as, an image or block of text, to be visible in the viewport. The recommended value is 2.5 seconds or less.

 

 

Multipurpose Internet Mail Extensions.
Used to identify the format of an internet resource. Internet infrastructure and browsers rely on the MIME value assigned to in the HTTP Content-Type header to ensure the resource is processed correctly. 'MIME type' values are managed by the Internet Assigned Numbers Authority and are based on the IETF RFC 6638. The full list of MIME types are listed at https://www.iana.org/assignments/media-types/media-types.xhtml.

 

 

Non-functional requirement.
Non-functional requirements (NFRs) Criteria used to evaluate the operation of a system and not its specific behavior. Covering four main aspects of operation NFRs describe how a system should perform not what it should do. The four aspects are Performance, Reliability, Scalability and Availability.

 

 

Observability.
A comprehensive concept that incorporates monitoring and benchmarking that provides analysis and interpretation of gathered data.

 

 

Open Systems Interconnection.
An ISO created set of standards enabling different varieties of computing systems to communicate seamlessy using standard communication protocols. A detailed description is available at Cloudflare's website.

 

 

Page Speed Insights.
Data captured by Google in it' Chrome User Experience Report (CrUX) dataset that enables the observation and classification of the user experience (UX) recieved from a web page.

 

 

Progressive Web App.
A method for installing a web application on a device. This enables the combination of features specific to websites and platform-specific apps. They are developed on a single codebase using standard web technologies and accessible on multiple operating systems.

 

 

Round Trip Time.
Measured in milliseconds it is the sum of the time taken for a request from the originating device to traverse the network to the requested server added to the time for the return trip back to the originating device. RTT is also known as Latency.

 

 

Real User Monitoring.
Captures metrics for analysis and evaluation of interactions with web pages by website visitors (Real Users). Comprehensive metrics are derived from the captured data enabling trends and patterns to be observed that can be used in optimising end-user satisfaction and website performance.

 

 

Single Page Application.
A method of interaction between the browser and server that dynamically rewrites the current page. By not loading an entire new page a smoother and more fluid UX is delivered similar to the look and feel of a natively installed application.

 

 

Sustainable Web Design Method.
The defacto method for calculating CO2e emissions of websites.

 

 

Transmission Control Protocol.
A transmission protocol used to establish network connection between network nodes and guarantee the exchange and delivery of data in the order in which they are sent between the connected network nodes. Fortinet.com defines TCP in greater deatil at TCP explained.

 

 

Transport Layer Security.
A security protocol used encrypt and decrypt data packets transmitted between network nodes. The protocol verifies the identities of the transmitter and receiver improving the integrity of the data being sent. Investigate TLS further with Cloudflare at TLS explained.

 

 

Time to First Byte.
Is calculated from the W3C Navigation Timing API as the difference between the `responseStart` and `navigationStart` timing points. Investigate TTFB further with Google at TTFB explained.

 

 

User Datagram Protocol.
A transmission protocol used to transmit packets of data (Datagrams) between network nodes without initially building a network connection between them. UDP can lose packets as it does not guarantee the exchange and delivery of data in the order in which they are sent. A detailed description from Cloudflare at UDP explained.

 

 

User Experience.
The experience received by the website visitor based on web page architecture and design, how it loads, and how they are able to interact with the web page. There are several methods for measuring this but Core Web Vitals are used by many as SEO and performance metrics.

 

 

Viewport.
The currently visable area of a web page is known as the viewport. On physical devices it is viewed through the screen. When processed by non-physical user-agents, such as a synthetic monitor, it can be considered as an area of memory that mimics a physical display and responds appropriately.

 

 

World Wide Web Consortium.
The World Wide Web Consortium (W3C) develops standards and guidelines to help everyone build a web based on the principles of accessibility, internationalization, privacy and security. Visit https://w3c.org for further information.

 

 

Web Assembly.
A binary instruction based language executing within a browser that supports the WebAssembly standard. It is highly portable and efficient code that delivers very fast performance and can interoperate with other languages such as JavaScript.

 

 

Web Vitals.
Web Vitals is a Google initiative that provides guidance on ensuring a great user experience when accessing websites. An important subset of the metrics collected and prosented are called Core Web Vitals.