Angular provides two ways to compile your application, Just-in-Time (JIT) and Ahead-of-Time (AOT).
Just-in-Time (JIT) Mode
Just in Time (JIT) compiler provides compilation during the execution of the program at a run time. In simple words, code get compiled when it is needed, not at the build time. In JIT mode, the angular compiler gets shipped to the browser.
Ahead-of-Time (AOT) Mode
The application is compiled ahead of time on the server side. The Ahead of Time (AOT) compiler converts the code during the build time before your browser downloads and runs that code.