What is the purpose of an assembler in programming?

The purpose of an assembler is to translate assembly language into machine code. Assembly language is a low-level programming language that is closely related to machine code but is more human-readable. It uses mnemonics and symbols that represent machine-level instructions, making it easier for programmers to write code compared to pure binary machine code.

When a programmer writes code in assembly language, it needs to be converted into machine code so that the computer's processor can execute it. An assembler performs this task, taking each assembly instruction and translating it into the corresponding binary representation. This process allows the high-level concepts expressed in assembly to be performed by the hardware, which can only understand machine code.

The other options do not accurately describe the function of an assembler. For example, converting high-level code into machine code involves a compiler, while debugging and designing user interfaces pertain to different aspects of software development altogether. Thus, the correct role of an assembler focuses specifically on the translation from assembly language to machine code.