Design Flow in VHDL
In VHDL design flow is composed of 3 steps:
Coding: The phase in which VHDL code is written. Designer may write the code from scratch or use IDE to make some of the code to be written by wizards.
Simulation: In this phase the prepared VHDL code is tested before downloading to the FPGA. By simulation possible errors are minimized.
Synthesis: In this phase, the VHDL code is translated to hardware, i.e. converted to RTL. This process is carried on by the synthesizers. But if you wish you can do it manually which would require advanced knowledge and heavy work for large designs.