What is server side rendering in Angular?

Server-side rendering (SSR) is a technique for rendering a client-side JavaScript framework, such as Angular, on the server instead of the client. When a user makes a request to a server-side rendered application, the server generates the HTML and JavaScript necessary to render the application on the client, and sends it to the client as a complete, fully-formed HTML document. This differs from the traditional approach of serving a basic HTML shell with JavaScript, which the client then uses to dynamically render the application.

There are several benefits to using server-side rendering with Angular:

• Improved performance: Server-side rendering can improve the initial load time of your application, as the HTML and JavaScript required to render the application is generated on the server and sent to the client, reducing the amount of work the client needs to do to display the content.
• Better SEO: Search engines have a difficult time indexing single-page applications, as they rely on JavaScript to render the content. With server-side rendering, the content is delivered to the search engine as fully-formed HTML, making it easier for search engines to index and understand the content.
• Improved accessibility: Screen readers and other assistive technologies rely on the HTML and JavaScript of a page to understand its structure and content. With server-side rendering, the content is available to these technologies as soon as the page loads, improving the accessibility of the application.

Implementing server-side rendering in Angular requires a special build process, as well as changes to the way the application is structured and managed. Angular provides a platform-agnostic library called Angular Universal, which provides the tools necessary to build server-side rendered applications. Additionally, there are several third-party tools and libraries that can help you implement server-side rendering in Angular, such as NestJS.

In summary, server-side rendering is a powerful technique for improving the performance, SEO, and accessibility of your Angular application. While it requires some effort to set up and maintain, the benefits it provides can be well worth the effort for many applications.