What back-end and front-end are in hardware design?
These are terms that refer to different stages of wafer processing. These expressions are typically written as "Back End of Line" (BEOL) and "Front End of Line" (FEOL) and refer to different stages of manufacturing. 


Front End of Line refers to "Front" or first part of a wafer manufacturing line. This is where all the wafer-based devices are formed, such as transistors, poly capacitors, non-metal resistors, and diodes. 
Back end of Line refers to the "Back" or last part of the manufacturing line. This is where the metal interconnection is added, as well as any top insulating layer. In addition, metal resistors, metal-metal capacitors, and inductors are build using these steps.