What Is SSG — Static Site Generation Explained for Beginners
In this tutorial, you will learn about What Is SSG. We cover key concepts, practical examples, and best practices to help you master this topic.
Static Site Generation pre-builds HTML pages at compile time, producing static files that load instantly from CDNs without server processing.
What You'll Learn
By the end of this tutorial, you'll understand what Static Site Generation is, how it differs from server-side rendering, the build process, and when SSG is the right choice for your project.
Why It Matters
Page speed directly impacts user experience and search rankings. SSG delivers the fastest possible load times because files are pre-built and served directly from CDNs. No server computation, no database queries — just pure HTML, CSS, and JavaScript delivered at network speed.
Real-World Use
A marketing website with 50 pages is rebuilt whenever content changes. Each page is pre-rendered as static HTML during build, deployed to a CDN, and served in milliseconds. The site handles traffic spikes effortlessly because every Visitor gets cached files from edge servers.
How SSG Works
graph LR
A[Content Source
Markdown / CMS / API] --> B[Build Process
Compile Time]
B --> C[Static HTML Files]
B --> D[CSS / JS Bundles]
B --> E[Asset Pipeline]
C --> F[CDN Deployment]
D --> F
E --> F
F --> G[User Browser]
style A fill:#4a90d9,color:#fff
style B fill:#e67e22,color:#fff
style F fill:#27ae60,color:#fff
style G fill:#2c3e50,color:#fff
Think of SSG like printing a book. You write all the content, design the layout, and print thousands of copies. Readers get identical, complete books instantly. No waiting for pages to be assembled on demand.
Build Process Example
// Simplified SSG build process
const fs = require('fs');
const path = require('path');
const { marked } = require('marked');
const contentDir = './content';
const outputDir = './public';
// Read all markdown content
const pages = fs.readdirSync(contentDir)
.filter(f => f.endsWith('.md'))
.map(file => {
const content = fs.readFileSync(path.join(contentDir, file), 'utf8');
const html = marked(content);
const slug = file.replace('.md', '');
return { slug, html };
});
// Generate static HTML files
pages.forEach(page => {
const template = `
<!DOCTYPE html>
<html>
<head><title>${page.slug}</title></head>
<body>
<nav><!-- static navigation --></nav>
<main>${page.html}</main>
<footer><!-- static footer --></footer>
</body>
</html>
`;
fs.writeFileSync(path.join(outputDir, `${page.slug}.html`), template);
console.log(`Generated: ${page.slug}.html`);
});
console.log(`Built ${pages.length} static pages.`);
Output:
Generated: index.html
Generated: about.html
Generated: contact.html
Generated: blog.html
Built 4 static pages.
Key SSG Features
// SSG framework configuration example (Next.js)
// next.config.js
module.exports = {
output: 'export', // Static HTML export
// Define routes to pre-render
async generateStaticParams() {
const posts = await fetch('https://api.example.com/posts').then(r => r.json());
return posts.map(post => ({
slug: post.slug,
}));
},
};
// SSG data fetching at build time
export async function getStaticProps({ params }) {
const res = await fetch(`https://api.example.com/posts/${params.slug}`);
const post = await res.json();
return {
props: { post },
// No revalidate — this is static. Rebuild to update.
};
}
SSG vs Other Rendering Approaches
const renderingApproaches = {
ssg: {
renderTime: 'Build time',
serverLoad: 'None (pre-built)',
contentFreshness: 'Requires rebuild',
useCase: 'Blogs, docs, marketing sites'
},
ssr: {
renderTime: 'Request time',
serverLoad: 'Per request',
contentFreshness: 'Always fresh',
useCase: 'E-commerce, dashboards, user content'
},
csr: {
renderTime: 'Client runtime',
serverLoad: 'Minimal (API only)',
contentFreshness: 'Depends on API',
useCase: 'Dashboards, admin panels, tools'
},
isr: {
renderTime: 'Build + periodic',
serverLoad: 'Revalidation only',
contentFreshness: 'Near real-time',
useCase: 'Large content sites, e-commerce'
}
};
Common Mistakes
- Choosing SSG for dynamic user content. If every user sees different data (dashboards, profiles), SSG requires generating millions of pages. Use SSR or CSR instead.
- Forgetting to rebuild on content change. SSG sites don't update automatically. You need a Webhook or CI/CD pipeline to trigger rebuilds when content changes.
- Building too many pages at once. Large sites with 100K+ pages can have multi-hour builds. Consider ISR or incremental builds for scale.
- Ignoring build-time data fetching limits. If your API rate-limits build requests, large sites may fail. Cache API responses locally during build.
- Serving dynamic features from static files. Forms, comments, search, and authentication need client-side JavaScript or external services. Don't expect server-side processing.
Practice Questions
- At what point in the lifecycle are SSG pages rendered?
- What is the main advantage of SSG over SSR for content-heavy sites?
- How do you update content on an SSG site after deployment?
- What happens to SSG performance during traffic spikes?
- When would SSG be a poor choice for a web application?
Challenge: Build a mini SSG from scratch that reads markdown files from a content/ directory, applies an HTML template, generates static files into a public/ directory, and prints a build summary.
FAQ
Mini Project
Create a personal blog using SSG principles: write 3 markdown posts in a content/ directory, create a build script that converts markdown to HTML with a shared template, generate an index page listing all posts, and deploy the output to Netlify or GitHub Pages.
What's Next
Now you understand SSG fundamentals. Compare it with Server-Side Rendering to understand when each approach works best.
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