Core Web Vitals

Core Web Vitals are metrics proposed by Google to evaluate the user experience of web pages. These metrics measure the performance and usability of web pages and also impact search rankings. Core Web Vitals consist of three main metrics:

1. LCP (Largest Contentful Paint)

Definition:

  • Measures the time it takes for the main content of a page to fully display.

Goal:

  • Ideally, LCP should occur within 2.5 seconds.

Improvement Strategies:

  • Reduce server response time

  • Optimize client-side rendering

  • Properly size and compress images and videos

  • Optimize CSS

2. FID(First Input Delay)

Definition:

  • Measures the time from when a user first interacts (clicks, taps, keystrokes, etc.) with the page to the time when the browser responds to that interaction.

Goal:

  • Ideally, FID should be within 100 milliseconds.

Improvement Strategies:

  • Optimize JavaScript

  • Minimize main thread work

  • Reduce the use of third-party code

3. CLS(Cumulative Layout Shift)

Definition:

  • Measures unexpected layout shifts during the loading of a page, evaluating issues where content moves unexpectedly while loading.

Goal:

  • Ideally, the CLS score should be less than 0.1.

Improvement Strategies:

  • Explicitly specify size attributes for images and videos

  • Reserve space for dynamic content

  • Prevent layout shifts caused by font loading

Importance of Core Web Vitals

  1. Improving User Experience:

    • These metrics aim to improve the loading speed, interactivity, and visual stability of web pages, enhancing the overall user experience.

  2. Impact on SEO:

    • Core Web Vitals are incorporated into Google's search ranking algorithms. Optimizing these metrics can improve search engine evaluation and potentially boost rankings.

  3. Increased Engagement and Conversion Rates:

    • When users can interact with pages without frustration, engagement improves, and conversion rates can increase.

Measuring Core Web Vitals

  1. Google Search Console:

    • You can check your site's performance through the Core Web Vitals report.

  2. PageSpeed Insights:

    • Measures LCP, FID, and CLS for each page and provides specific improvement suggestions.

  3. Lighthouse:

    • Available as part of developer tools, it offers analysis of web page performance, accessibility, and SEO.

  4. Web Vitals Extension:

    • Provided as a browser extension, it measures Core Web Vitals in real-time.

Specific Improvement Examples

  1. Improving LCP:

    • Reduce Server Response Time

      : Use fast hosting services and leverage caching.

    • Optimize Client-Side Rendering

      : Delay load CSS and JavaScript, and initially load only essential resources.

  2. Improving FID:

    • Optimize JavaScript

      : Split large JavaScript files and delay load, loading only necessary parts before user interaction.

    • Reduce Main Thread Load

      : Minimize heavy processing on the main thread, utilize offscreen processing, and employ Web Workers.

  3. Improving CLS:

    • Specify Sizes for Images and Ads

      : Explicitly define sizes for media elements to ensure layout stability.

    • Reserve Space for Dynamic Content

      : Pre-allocate space for dynamically inserted content to prevent unexpected layout shifts.

Core Web Vitals are crucial metrics for enhancing user experience. Optimizing these metrics can significantly improve website performance, leading to increased user satisfaction, improved search engine rankings, and higher engagement.