PHP is a very popular programming language that is often used for web application development. There are many PHP frameworks available on the market, each with its own features and benefits. Some of the most popular and used PHP frameworks in 2023 are:

Laravel

Laravel is one of the most popular and comprehensive PHP frameworks available. It offers a large number of tools and features to make web application development easier, such as a large number of pre-built libraries and packages, an easy-to-use command-line interface, and a flexible template system.

websites that use Laravel: Envato, LinkedIn, MyHeritage, TourRadar

Pros:

1.It is easy to learn: Laravel has clear and complete documentation, which makes it easy for developers to learn.

2. It offers great performance: Laravel is designed to be fast and efficient, which makes it ideal for large-scale projects.

3. Provides a large number of tools: Laravel includes a large number of useful tools for developers, such as the Composer dependency manager and the Blade template system.

4. It has a great community: Laravel has a great community of developers who contribute to the framework and keep it up to date. This means that there are many resources available for learning and troubleshooting.

Cons:

1. Can be a bit complex: Laravel offers many options and features, which can be a bit overwhelming for new users.

2. It can be heavy: Laravel comes with a large number of features and dependencies, which can make the final application heavier than it might be with another framework.

3. Can be expensive – Laravel can be a more expensive option for small projects due to the number of tools and features it includes.

CodeIgniter

CodeIgniter is a lightweight and easy to use PHP framework that focuses on simplicity and speed of development. It is ideal for small and medium projects and is characterized by being very easy to learn.

websites that use CodeIgniter: British Airways, EllisLab, British Council

Pros:

1. It's easy to use: CodeIgniter has a relatively low learning curve, making it accessible for beginning developers.

2. It's light and fast: CodeIgniter is a light and efficient framework, which makes it ideal for smaller scale projects or for applications that require fast performance.

3. It is highly configurable: CodeIgniter allows developers to configure and customize the framework according to their needs.

4. It has a large community: Like Laravel, CodeIgniter has a large community of developers who contribute to the framework and keep it up to date.

Cons:

Offers fewer features: CodeIgniter is a lighter framework than Laravel and as such offers fewer features and tools to developers.

May be less secure: Although CodeIgniter includes some security features, it may be less secure than other frameworks due to its focus on ease of use and performance.

Can be less flexible: CodeIgniter is less flexible than other frameworks and can be more difficult to adapt to larger projects or projects with specific requirements.

Symfony

 Symfony is a very complete and mature PHP framework that is often used for large-scale projects. It offers a large number of advanced tools and features to facilitate the development and maintenance of web applications.

websites that use Symfony: BlaBlaCar, Dailymotion, Yahoo! Japan

Pros:

1. It is very complete: Symfony includes a large number of tools and features for developers, which makes it very complete and versatile.

2. It is highly scalable: Symfony is designed for large-scale projects and is highly scalable, making it ideal for applications that need robust and consistent performance.

3. It is highly modulable: Symfony is divided into individual modules, allowing developers to choose and use only the features they need for their project.

4. It has a large community: Like Laravel and CodeIgniter, symfony has a large community of developers who contribute to the framework and keep it up to date.

Cons:

1. It can be difficult to learn: Symfony is a very complete framework and it can be difficult for new users to learn.

2. It can be heavy: Due to its large number of features and tools, symfony can be a heavy framework and can make the final application larger than it could be with another framework.

3. It can be expensive: Like Laravel, symfony can be a more expensive option for smaller projects due to the number of tools and features it includes.

Zend Framework

 The Zend Framework is another very complete and powerful PHP framework that is often used for large scale projects. It offers a large number of advanced tools and features to facilitate the development and maintenance of web applications.

websites that use Zend Framework: Adobe, Cisco, Nokia

Pros:

1.It is very complete: The Zend Framework includes a large number of tools and features for developers, which makes it very complete and versatile.

2.It is very secure: Zend Framework is designed with security in mind and offers a large number of security features to protect applications.

3.It is highly customizable: Zend Framework allows developers to customize and configure the framework according to their needs.

4. It has a large community: Like Laravel, CodeIgniter, and Symfony, the Zend Framework has a large community of developers who contribute to the framework and keep it up to date.

Cons:

1. It can be difficult to learn: Like symfony, the Zend Framework is a very complete framework and can be difficult for new users to learn.

2. It can be heavy: Due to its large number of features and tools, the Zend Framework can be a heavy framework and can make the final application larger than it could be with another framework.

3. It can be expensive: Like Laravel and Symfony, the Zend Framework can be a more expensive option for smaller projects due to the number of tools and features it includes.

It's important to note that there is no overall "best" PHP framework, as each has its own strengths and weaknesses and is suitable for different types of projects. It is best to evaluate which of these frameworks best fits the needs of your project and choose accordingly.