A project is declared with project(name), and targets are the build artifacts you create — executables, libraries, or custom outputs. Each target has properties (source files, include paths, linked libraries, compiler flags). In modern CMake, you apply settings to targets, not globally.

A project groups related targets:

cmake_minimum_required(VERSION 3.20)
project(MyApp VERSION 1.0)
 
add_executable(myapp main.cpp)
add_library(mylib utils.cpp)

This creates a project MyApp with two targets: the executable myapp and a library mylib.

Target types:

• add_executable(name source.cpp) — builds an executable
• add_library(name source.cpp) — builds a library (static by default)
• add_library(name SHARED source.cpp) — shared library (.so, .dll)
• add_library(name STATIC source.cpp) — static library (.a, .lib)
• add_library(name INTERFACE) — header-only library (no build, only interface)
• add_custom_target(name COMMAND ...) — runs a command (not a traditional build output)

Each target owns its properties: source files, include directories, linked libraries, compiler flags. Properties are set with target_* commands:

target_sources(mylib PRIVATE utils.cpp utils.h)
target_include_directories(mylib PUBLIC include/)
target_link_libraries(mylib PRIVATE somelib)
target_compile_options(mylib PRIVATE -Wall)

The PRIVATE, PUBLIC, INTERFACE keywords control visibility:

• PRIVATE — only the target itself uses it
• PUBLIC — target and anything that links to it use it
• INTERFACE — only consumers of the target use it (for header-only libraries)

Modern CMake means thinking in targets. Don't set global flags with set(CMAKE_CXX_FLAGS ...). Instead, configure each target individually. This makes builds predictable and modular.