100% Free Forever
AI-Powered Learning
Industry Expert Content
Certificates & Badges
Learn At Your Own Pace
Programming

PNG

By PNG Development Group / W3C

BeginnerProtocol1.8K learners

PNG (Portable Network Graphics) is a raster image file format that uses lossless compression, meaning an image can be saved and reopened without any loss of pixel detail, and it natively supports full alpha-channel transparency. It was…

#PNG#Programming#Protocol#Beginner#JPEG#GIF#TIFF#Webpack#SoftwareDevelopment#Glossary#SkillVeris

Definition

PNG (Portable Network Graphics) is a raster image file format that uses lossless compression, meaning an image can be saved and reopened without any loss of pixel detail, and it natively supports full alpha-channel transparency. It was created as a free, patent-unencumbered replacement for GIF after a licensing dispute over GIF's compression algorithm in the mid-1990s, and it has since become one of the most widely used image formats on the web and in software for icons, screenshots, and graphics requiring transparency.

Overview

PNG was developed in response to a licensing controversy: GIF, the dominant lossless web image format at the time, used LZW compression, which was covered by a patent that Unisys began enforcing against software vendors in 1994, creating uncertainty for anyone shipping GIF-encoding software. A group of developers created PNG as an openly specified, royalty-free alternative that improved on GIF technically as well, adding true alpha transparency (GIF only supports binary on/off transparency) and support for far more colors than GIF's 256-color palette limit, while using a different, unencumbered compression method. Mechanically, PNG compresses image data using DEFLATE, the same lossless compression algorithm used by zip and gzip, applied after a preprocessing step called filtering that transforms each row of pixels based on neighboring pixel values to make the data more compressible before DEFLATE runs on it. Because DEFLATE is lossless, decompressing a PNG reconstructs the exact original pixel data with no degradation, unlike JPEG's lossy compression which discards information to achieve smaller file sizes. PNG supports several color modes, including full 24-bit truecolor with an optional 8-bit alpha channel for transparency, 8-bit palette-based indexed color similar to GIF, and grayscale, giving it flexibility across different image types. Among image formats, PNG occupies the lossless, general-purpose slot: it's typically the right choice for screenshots, diagrams, logos, icons, and any image with sharp edges, text, or transparency, where JPEG's lossy compression would introduce visible artifacts around hard edges. JPEG remains the better choice for photographic images where some quality loss is acceptable in exchange for much smaller file sizes, since PNG's lossless compression produces far larger files for photo-like content with lots of color gradation and noise. WebP and AVIF are newer formats that can match or beat PNG's lossless compression ratios and also offer lossy modes, and have been gaining ground as browser support has matured, though PNG remains near-universally supported across all software and hardware. In practice, PNG is the default format for website UI elements, logos, and any image needing transparency, for screenshots taken by nearly every operating system, and for any raster asset produced by design tools that must not lose quality through repeated edits and re-saves the way JPEG would. It is also embedded as an interchange format inside many document, presentation, and file formats. The main trade-off is file size on photographic content: because PNG cannot discard information the way JPEG does, a photo saved as PNG is typically several times larger than the same photo saved as a reasonably compressed JPEG, with no visible quality benefit for a source that is already a lossy photograph. For that reason, most web and application workflows still choose JPEG or newer lossy formats for photographs and reserve PNG for graphics, transparency, and lossless-fidelity needs.

Specification

  • Lossless compression preserving exact original pixel data
  • Full alpha-channel transparency support, unlike GIF's binary transparency
  • Uses DEFLATE compression with row-based filtering preprocessing
  • Supports truecolor, indexed-palette, and grayscale color modes
  • Patent-free, openly specified format free to implement
  • Near-universal support across browsers, operating systems, and software
  • Repeated saves do not degrade image quality

Use Cases

Displaying logos and icons requiring transparent backgrounds
Capturing and sharing operating system screenshots
Storing diagrams and UI graphics with sharp edges and text
Embedding lossless raster assets in documents and presentations
Iteratively editing images without cumulative quality loss
Serving website graphics that need crisp, artifact-free rendering

Alternatives

Frequently Asked Questions

Frequently Asked Questions

21 categories · pick one to explore

Does SkillVeris have a tech blog, and what does it cover?
Yes, the SkillVeris blog has over 500 articles covering AI and machine learning, programming, web development, DevOps, cloud, security, databases and career guidance. Articles are practical and answer-first, and many use the Learn Through Hobbies approach, teaching technical concepts through cricket, music, gaming or cooking analogies. Everything is free to read.
What is the SkillVeris tech glossary and how big is it?
The SkillVeris glossary is a free reference of roughly 2,000-plus technology terms, each with a clear plain-language definition. It spans AI, programming, web, DevOps, cloud, security and database vocabulary, so whenever a lesson, article or job description uses jargon you do not recognise, the glossary gives you a fast, reliable answer.
Are the developer cheat sheets on SkillVeris free to download?
The cheat sheets are completely free to use, like everything else on SkillVeris. Each sheet condenses a language or tool into its essential syntax, commands and patterns for quick reference while coding. They are designed for rapid lookup during real work, complementing the deeper explanations found in study notes and courses.
Which programming references and cheat sheets are available?
Cheat sheets cover the platform's main domains, including programming languages, AI and ML tooling, web development, DevOps, cloud, security and databases, matching the topics of the 37 live courses. Each sheet lists related reading links and hashtags, so you can jump from a quick reference into fuller study notes or blog articles.
How do I find the meaning of a technical term quickly?
Search the SkillVeris glossary, which holds around 2,000-plus terms with concise, plain-language definitions. Each entry gets to the point in its first sentence, then links to related reading like blog posts or study notes for deeper context. It is faster and more consistent than sifting through scattered search results.
Is the SkillVeris blog good for beginners learning to code?
Yes, many blog articles are written specifically for beginners, and the Learn Through Hobbies style makes them unusually approachable: you might learn Python concepts through cricket or understand APIs through cooking. With 500-plus articles across skill levels, beginners can start with fundamentals and keep reading as they advance, entirely free.
Can cheat sheets replace full courses for learning a language?
No, cheat sheets are references, not teaching tools; they assume you already understand the concepts and just need syntax or commands fast. To actually learn a language, take a structured SkillVeris course with its 24–40 lessons and assessments, then keep the cheat sheet beside you while practising in Code Lab.
How often are new blog articles published on SkillVeris?
The blog grows regularly and already exceeds 500 articles, with new posts added as courses launch and technologies evolve. Topics track the platform's catalogue across AI, programming, web development, DevOps, cloud and security, so checking the Blog section periodically surfaces fresh tutorials, explainers and career-focused pieces, all free to read.
Does the glossary cover AI and machine learning terms?
Yes, AI and machine learning vocabulary is a major part of the roughly 2,000-plus term glossary, covering everything from foundational terms to modern concepts around LLMs, RAG and MLOps. Definitions are plain-language and answer-first, which helps when dense AI papers or course lessons throw unfamiliar jargon at you.
Are there cheat sheets for interview preparation?
Cheat sheets work well as interview-day refreshers because they compress syntax, commands and key concepts into scannable references. For dedicated preparation, combine them with the SkillVeris interview questions feature, which includes readiness scoring, plus study notes for depth. Reviewing a relevant cheat sheet just before an interview steadies recall under pressure.
Can I read the tech blog without signing up?
Yes, the blog is freely readable, and SkillVeris never charges for content. All 500-plus articles are open, covering tutorials, concept explainers and career advice. Creating a free account adds value elsewhere on the platform, like course progress tracking and certificates, but reading the blog requires no commitment at all.
How is the SkillVeris glossary different from Wikipedia?
The glossary is purpose-built for learners: definitions are short, plain-language and answer-first, sized for a quick lookup mid-lesson rather than a deep encyclopedic read. Entries also cross-link to related SkillVeris study notes, blog posts and courses, so a definition becomes a doorway into structured learning instead of a dead end.
Do blog articles use the Learn Through Hobbies method?
Many blog articles teach technical topics through hobby analogies, a hallmark of the SkillVeris blog, so you will find articles explaining programming through cricket, machine learning through music, or system design through cooking. The analogy is the teaching device; the article still delivers the real technical concept underneath.
Where can I find quick programming references while coding?
Open the SkillVeris cheat sheets, which are built exactly for that moment: compact, scannable references for syntax, commands and common patterns across languages and tools. Keep the relevant sheet in a browser tab while you work in Code Lab or your own editor, and dip into the glossary for terminology.
Is there a glossary entry for terms I meet in job descriptions?
Very likely yes, with roughly 2,000-plus terms across AI, programming, web, DevOps, cloud, security and databases, the glossary covers most jargon that appears in tech job descriptions. Decoding a listing this way helps you judge role fit honestly and prepares you to discuss those terms in interviews.
Are the blog articles written for the Indian tech audience?
The blog serves Indian learners plus a worldwide audience. Content stays globally relevant while acknowledging realities that matter in India, such as free access being essential for students and freshers, and career guidance that connects naturally to the SkillVeris jobs portal, which aggregates roles across India, UK, USA, Germany and Remote.
Can I suggest a topic for the blog or glossary?
SkillVeris content grows in response to what learners need, so feedback is welcome through the platform's support channels. If a term is missing from the glossary or a topic deserves an article, telling the team helps prioritise it. Meanwhile, the AI Mentor can answer the question immediately, 24/7, at any depth.
Do cheat sheets and glossary entries link to deeper learning?
Yes, every cheat sheet and glossary entry carries related reading links into study notes, blog articles and courses, plus concept hashtags for discovering similar content. This cross-linking means a thirty-second lookup can smoothly become a structured learning session whenever you decide you want more than a quick answer.
What makes SkillVeris programming references trustworthy?
The references are written to strict internal quality standards, kept consistent with the platform's 37 live courses, and never padded with invented statistics or hype. Definitions and cheat sheets are reviewed against the same content contracts that govern courses, and the answer-first style makes any inaccuracy easy to spot and correct.
How do the blog, glossary and cheat sheets fit into my learning routine?
Use them as satellites around your main course: read blog articles for context and motivation, hit the glossary the instant jargon appears, and keep cheat sheets open while coding. Together with study notes, Code Lab and the 24/7 AI Mentor, they turn passive reading into a complete, free learning system.

What Learners Say

Real journeys from the SkillVeris community — swipe for more.

SkillVeris taught me Python through Cricket. Now I’m building real projects and feeling confident!
Arjun S. · B.Tech Student
The best platform for hobby-based learning. Concepts finally stick.
Priya R. · Data Analyst
I went from zero coding to a portfolio of projects — all by learning through my love for gaming. Landed my first internship!
Kabir M. · CS Undergraduate
Trending Topics50 popular tags — tap to explore
Trending CoursesAll 37 free courses — tap to browse