That’s a great question to have proper knowledge about plugin.

However, I’ve listed some highly recommended plugins for popular functionalities:

1. SEO (Search Engine Optimization):
   • Yoast SEO: One of the most popular SEO plugins, Yoast SEO offers a range of features such as content analysis, XML sitemaps, and meta tags to help optimize your website for search engines.
   • All in One SEO Pack: Similar to Yoast SEO, All in One SEO Pack provides comprehensive SEO features including XML sitemap support and automatic optimization options.
2. Caching and Performance Optimization:
   • WP Rocket: Known for its powerful caching capabilities, WP Rocket boosts website speed and performance by implementing page caching, file compression, and other optimization techniques.
   • W3 Total Cache: A widely used caching plugin, W3 Total Cache helps improve website performance by caching pages and assets, reducing load times, and integrating with content delivery networks (CDNs).
3. Contact Forms:
   • Contact Form 7: A popular and versatile plugin, Contact Form 7 allows you to create and manage multiple contact forms easily and customize their fields and appearance.
   • WPForms: Known for its user-friendly interface, WPForms offers a drag-and-drop form builder, pre-built form templates, and features like conditional logic and spam protection.
4. E-commerce:
   • WooCommerce: The leading e-commerce plugin, WooCommerce enables you to set up and manage an online store with features for product management, secure payments, inventory tracking, and more.
   • Easy Digital Downloads: Designed specifically for digital products, Easy Digital Downloads simplifies the process of selling and managing digital downloads, offering extensive customization options.
5. Social Media Sharing:
   • Shared Counts: With Shared Counts, you can add social sharing buttons to your website, allowing visitors to easily share your content across various social media platforms.
   • AddToAny: A popular social sharing plugin, AddToAny provides customizable sharing buttons that can be integrated into your website to encourage social sharing.
6. Security:
   • Wordfence Security: This comprehensive security plugin helps protect your website from malware, provides firewall protection, and offers various security features to safeguard your WordPress site.
   • Sucuri Security: Sucuri Security offers website monitoring, malware scanning, and security hardening features to keep your website secure from potential threats.
7. Image Optimization:
   • Smush: Smush is a widely used plugin that optimizes and compresses images on your website to improve performance without sacrificing quality.
   • ShortPixel: ShortPixel is another popular image optimization plugin that reduces image file sizes, helping to enhance page load times and overall site performance.
8. Page Builders:
   • Elementor: Elementor is a powerful drag-and-drop page builder that allows you to create visually stunning designs and layouts without any coding knowledge.
   • Beaver Builder: Known for its user-friendly interface, Beaver Builder offers a range of pre-built templates and modules for easy customization and page building.
9. Backup and Restore:
   • UpdraftPlus: UpdraftPlus simplifies the process of creating backups for your WordPress site and allows you to easily restore your website if needed.
   • BackWPup: BackWPup enables you to schedule automatic backups, store them in various locations, and restore your website with just a few clicks.
10. Analytics and Tracking:
    • Google Analytics for WordPress by MonsterInsights: This plugin integrates Google Analytics into your WordPress site, providing detailed website statistics and tracking information.
    • Jetpack by WordPress.com: Jetpack includes a module for site statistics and analytics, giving you insights into your website’s traffic, popular content, and more.