# CMake Projects and Targets

**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
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:

```cmake
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.