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Images now make up nearly 50% of a typical website's total page weight . In an era where both  user experience and search engine rankings are tied to page speed , optimizing images is no longer a luxury—it's a necessity. This article will guide you through two powerful techniques to address this: implementing responsive images with srcset and converting your entire library to the modern WebP format . Illustration: A webP image Why Your Website Needs Responsive Images The "one-size-fits-all" approach to images is broken. Serving a massive, high-resolution desktop image to a mobile user wastes bandwidth and slows loading times . Conversely, stretching a small image on a high-resolution screen makes it look blurry or pixelated . Responsive image technologies solve two main problems: The Art Direction Problem : Delivering a differently cropped or composed image depending on the display size. For example, a wide header image on desktop might be cropp...

Want to glue Python to the rest of your system  -  call a compiled program, run a shell script, invoke Node.js, call Java, or pipe data to/from R? Enter subprocess . It’s Python’s standard way to start external programs, control their input/output, check return codes, set environments and timeouts — all with a solid API. Below is a practical, friendly guide: what subprocess is, why you’d use it, examples, best practices, pitfalls, and which languages/tools you can call from it. What is subprocess ? subprocess is a standard Python module that lets your Python program spawn new processes, connect to their input/output/error pipes, and obtain their return codes. It replaces older modules like os.system , popen and friends with a unified, safer interface. Key high-level primitives: subprocess.run() — simple, recommended for most cases (Python 3.5+). subprocess.Popen — lower-level, use when you need streaming IO, advanced control, or long-lived processes...