This paper presents the capabilities of the FreeFem++ software, focusing on its features and applications in solving partial differential equations (PDEs). FreeFem++ is a free, open-source software based on the Finite Element Method (FEM), designed for solving PDEs in two and three dimensions. It supports a wide range of functionalities, including mesh adaptation, solving complex problems with nonlinearities, and parallel computing. The software allows users to describe problems using variational formulations and provides tools for mesh generation, adaptive mesh refinement, and solving linear and nonlinear systems. The paper discusses several key aspects of FreeFem++. It begins with an introduction to the software, highlighting its ability to handle various types of PDEs, including elliptic, parabolic, and hyperbolic problems. It then describes the weak formulation of PDEs and provides an example of solving a Poisson problem. The paper also covers mesh adaptation techniques, including anisotropic mesh adaptation based on a metric, and presents an example of mesh adaptation for a Poisson problem in an L-shaped domain. The paper further discusses the solution of a phase change problem with natural convection, which involves coupling fluid dynamics with solid-phase change. This example demonstrates the software's capability to handle complex, nonlinear problems. The paper also presents a Schwarz domain decomposition example in parallel computing, showing how the software can be used for large-scale problems with parallel processing. In conclusion, FreeFem++ is a powerful tool for solving a wide range of PDEs, with features that support mesh adaptation, parallel computing, and handling of complex, nonlinear problems. The software is continuously evolving, with new features and tools being added to enhance its capabilities. The paper highlights the versatility and effectiveness of FreeFem++ in solving various scientific and engineering problems.This paper presents the capabilities of the FreeFem++ software, focusing on its features and applications in solving partial differential equations (PDEs). FreeFem++ is a free, open-source software based on the Finite Element Method (FEM), designed for solving PDEs in two and three dimensions. It supports a wide range of functionalities, including mesh adaptation, solving complex problems with nonlinearities, and parallel computing. The software allows users to describe problems using variational formulations and provides tools for mesh generation, adaptive mesh refinement, and solving linear and nonlinear systems. The paper discusses several key aspects of FreeFem++. It begins with an introduction to the software, highlighting its ability to handle various types of PDEs, including elliptic, parabolic, and hyperbolic problems. It then describes the weak formulation of PDEs and provides an example of solving a Poisson problem. The paper also covers mesh adaptation techniques, including anisotropic mesh adaptation based on a metric, and presents an example of mesh adaptation for a Poisson problem in an L-shaped domain. The paper further discusses the solution of a phase change problem with natural convection, which involves coupling fluid dynamics with solid-phase change. This example demonstrates the software's capability to handle complex, nonlinear problems. The paper also presents a Schwarz domain decomposition example in parallel computing, showing how the software can be used for large-scale problems with parallel processing. In conclusion, FreeFem++ is a powerful tool for solving a wide range of PDEs, with features that support mesh adaptation, parallel computing, and handling of complex, nonlinear problems. The software is continuously evolving, with new features and tools being added to enhance its capabilities. The paper highlights the versatility and effectiveness of FreeFem++ in solving various scientific and engineering problems.