Below a list of 20 popular WordPress plugins along with their primary uses:

1. Yoast SEO (Plugin URL): Optimizes your website for search engines with tools for meta tags, sitemaps, and content analysis.

2. Akismet Anti-Spam (Plugin URL): Protects your site from spam comments and contact form submissions.

3. WooCommerce (Plugin URL): Transforms your website into an e-commerce platform, allowing you to sell products and services.

4. Jetpack (Plugin URL): Provides a suite of tools for website security, performance optimization, and site management.

5. Contact Form 7 (Plugin URL): A versatile plugin for creating and managing contact forms on your site.

6. Wordfence Security (Plugin URL): Offers firewall protection, malware scanning, and login security to safeguard your site.

7. MonsterInsights (Plugin URL): Integrates Google Analytics with your WordPress site for detailed insights into your traffic.

8. UpdraftPlus (Plugin URL): Simplifies website backups, allowing you to schedule and restore backups with ease.

9. Elementor (Plugin URL): A drag-and-drop page builder that helps you create custom page layouts and designs.

10. Smush (Plugin URL): Automatically optimizes and compresses images to improve site performance.

11. WP Super Cache (Plugin URL): Speeds up your site by creating static HTML files and reducing server load.

12. Redirection (Plugin URL): Manages 301 redirects to handle broken links and improve SEO.

13. All in One SEO Pack (Plugin URL): A comprehensive SEO plugin for optimizing meta tags, XML sitemaps, and more.

14. Sucuri Security (Plugin URL): Offers website security monitoring, malware scanning, and a website firewall.

15. WPForms (Plugin URL): A user-friendly form builder for creating contact forms, surveys, and other types of forms.

16. W3 Total Cache (Plugin URL): Improves site speed and performance by caching content and minifying scripts.

17. TablePress (Plugin URL): Allows you to create and manage tables in your posts or pages without coding.

18. The Events Calendar (Plugin URL): Enables you to create and manage events, making it suitable for event-based websites.

19. Advanced Custom Fields (Plugin URL): Enhances content editing by adding custom fields and metaboxes to your posts and pages.

20. Post to Post Links II (Plugin URL): Provides an easy way to create relationships between different post types, making it useful for content structuring.

These plugins cover a wide range of functionalities and can be valuable additions to your WordPress website. Always ensure that you choose plugins that align with your specific needs and goals.

Also:

• Posts 2 Posts: Allows many-to-many relationships between posts with optional link info. Plugin URL

• Fast Secure Contact Form: Enables quick contact forms sent via email. A nice companion plugin is the database storage plugin to store entries to a database. Plugin URL

• Custom Content Type Manager: Easily adds multiple content types, providing multiple custom field types that are repeatable. Plugin URL

• Google Analytics: Helps you keep track of visitors to your website. Plugin URL

• Google AdSense: Allows you to put ads on your website. Plugin URL

• W3 Total Cache: Helps improve website performance when performance issues arise. Plugin URL

• WP Mail SMTP: Many hosts either provide no mail server or their IP is blocked from sending mail. This plugin allows you to send email via an alternate provider such as Gmail. Plugin URL

• WordPress SEO by Yoast: This plugin, among others, rewrites headers to be more search engine-friendly. An alternative is All in One SEO Pack, which has been around much longer but has been losing popularity. Plugin URL

• NextGEN Gallery: For all times you need to add picture galleries, this is a good option. Many extensions to add flexibility exist, such as voting. Plugin URL

These plugins offer various functionalities to enhance and customize your WordPress website according to your specific needs. Make sure to install and configure them correctly to optimize your site's performance and functionality.