Linux server control panels are software tools that provide a graphical user interface to help manage various aspects of a Linux server. They allow you to easily administer things like user accounts, websites, databases, security settings and more through a web browser rather than needing to use the Linux command line. Some of the most popular Linux control panels include cPanel, Plesk, DirectAdmin, Webmin, Virtualmin and ISPConfig. Here is an overview and comparison of these different options:

cPanel

cPanel is one of the most widely used Linux control panels, particularly among web hosting companies. It provides a very user-friendly interface for managing domains, email accounts, FTP accounts, databases and more. Some key features of cPanel include:

- Automated installer scripts (EasyApache) for configuring Apache, PHP and other components. This makes it easy to optimize your server software and keep it updated.

- Powerful features for managing emails including spam filters, auto-responders, mailing lists and cross-domain email routing. cPanel also integrates with external email services like G Suite.

- Built-in security tools like mod_security firewall, hotlink protection and Leech Protect for blocking abusive bots/scrapers.

- Simple DNS management for adding/editing DNS zones and records. Supports integration with external DNS services. 

- Supports virtual hosts for running multiple websites on a single server. Makes it easy to set up new domains and subdomains.

- One-click installers for applications like WordPress, Drupal, Joomla. Also easy deployment of web apps from Git repositories.

- cPanel is not open source though they have released an automated installer tool called cPanel & WHM Scripts. Pricing for cPanel licenses tends to be higher compared to other control panels.

Plesk

Plesk is another commercial Linux hosting control panel that competes with cPanel. Key features include:

- GUI for managing websites, emails, DNS, FTP, databases and more across unlimited domains. Centralized control of all web hosting features.

- Integrated website builder, SEO tools, security advisor, traffic analytics and monitoring. Makes it easy for users without technical expertise to manage a website.

- Multi-server management allows administering multiple servers through a single Plesk instance. 

- Deployment manager and Git/SVN integration simplifies deploying web apps and managing code changes.

- Scales well for resellers/ISPs with ability to create separate client accounts and resell hosting services.

- Extensions marketplace adds new functionality like server monitoring, cloud storage syncing, marketing tools and more.

- Compatible with PostgreSQL, MySQL, MS SQL databases. Database tools like phpMyAdmin built-in. 

- Plesk is a commercial product but offers a free trial for testing. Comes in different tiered pricing plans.

DirectAdmin

DirectAdmin is an alternative control panel focused on simplicity and performance. Some notable aspects:

- Lightweight architecture makes it one of the fastest control panels available. Minimal server overhead.

- Auto-installers for Apache, PHP, MySQL, Exim, FTP, and other applications for quick setup. Keeps software up-to-date.

- User-friendly interface allows clients to easily manage hosting accounts, email, DNS zones, databases and more by themselves. 

- Includes CloudLinux OS integration for improved security and resource management. Gives each account guaranteed CPU and memory resources.

- Daily backups built-in with ability to restore files/accounts. Other security features like firewall configuration and rootkit detection.

- Supports add-ons and skins to extend functionality or customize look and feel. API available for external integration.

- DirectAdmin is free and open source. Basic version has no user limits or feature restrictions. Paid "DirectAdmin Extended" adds premium support and other enterprise features.

Webmin

Webmin is an open source web-based Linux administration tool and one of the oldest control panels available. Here are some key highlights:

- Provides modules for configuring most common Linux server services like Apache, DNS, file/FTP servers, databases and more. All accessible through web UI.

- Ability to administer local or remote Linux servers and manage users/groups across different systems. 

- Additional modules extend functionality to things like firewall configuration, cluster/cloud management, Docker containers, webmail and more.

- Webmin modules typically edit underlying config files directly rather than relying on abstract APIs. This can make it lightweight but also more prone to breaking things if not careful.

- Has theme support to customize look and feel. Modules can be added/removed easily. Access controls allow delegating privilege.

- Lack of commercial support and development for many years resulted in dated interface and vulnerabilities. Recent efforts have led to revival with improved security and maintenance.

- Webmin is open source and free to use. Required dependencies like Perl can make setup more complex compared to modern control panels however.

Virtualmin

Virtualmin is an add-on module for Webmin that turns it into more of a web hosting control panel. Adds useful features like:

- Virtual hosting tools make it easy to setup and manage domains and websites. Includes Apache configuration, PHP/CGI, access controls etc.

- Integrated mail server with spam filtering, webmail access, mailing lists, auto-responders and quotas.

- Built-in File Manager, Web Calendar, Wiki, CMS and other web apps for each domain. Apps stay updated within Virtualmin. 

- Backups and restoration for websites, emails, MySQL databases integrated seamlessly. Clone/migrate sites between servers.

- Integrates with external DNS control panels like Cloudflare and BIND9 for easier domain management. 

- Other advanced capabilities like server templates, SSO authentication, REST API access, IP/name-based virtual hosts etc.

- Virtualmin is open source and built on Webmin so it inherits the same strengths and weaknesses. The combination provides a pretty robust set of hosting tools however.

ISPConfig

ISPConfig is a Linux hosting control panel similar to Virtualmin built on top of Webmin and specialized for Internet Service Providers. Key features:

- Multi-server/multi-tenant capable with centralized management of infrastructure. Makes it great for managed hosting providers.

- Automated management and deployment of customer websites, emails, DNS zones, databases and other resources.

- Integrated billing and invoice generation based on resource usage. Supports prepaid/credit-based account limits.

- Advanced HTTPd, DNS, DHCP services with HA clustering support and automatic recovery. 

- Custom branding, templating and reseller account management for white-label ISP offerings. Public customer self-service interface.

- ISPConfig also open source built on Webmin/Virtualmin. It provides more ISP-oriented structure and features compared to Virtualmin alone.

In summary, while all aiming to simplify Linux server management, control panel solutions differ quite a bit in their technical implementation, features, performance, pricing and use-cases. cPanel and Plesk are popular commercial options with rich features and support. DirectAdmin provides a very fast and lightweight option. Webmin, Virtualmin and ISPConfig are open source tools that, together, provide an extremely flexible hosting platform. The "best" option depends on your specific hosting environment and requirements. Properly configuring any control panel takes some learning and expertise so you can make the most of it. But ultimately they can save a lot of time and effort compared to managing Linux servers manually.