Explanation:
CISC stands for Complex Instruction Set Computer. It is a type of computer architecture that uses a large number of complex instructions. The term "complex" refers to the fact that these instructions can perform multiple operations or manipulate complex data structures in a single instruction.

Characteristics of CISC architecture:
CISC architecture has several key characteristics that distinguish it from other types of computer architectures:

1. Large instruction set: CISC processors typically have a large number of instructions, each of which can perform complex operations. This allows for a wide range of operations to be performed directly by the hardware.

2. Variable instruction length: Instructions in a CISC architecture can have different lengths, depending on their complexity. This allows for more flexibility in encoding complex operations.

3. Memory-to-memory operations: CISC processors often support instructions that can perform operations directly on data stored in memory, rather than requiring data to be loaded into registers first. This can reduce the number of memory accesses and improve performance.

4. Microcode implementation: CISC processors often use microcode, which is a low-level software layer that translates complex instructions into simpler microoperations that can be executed by the hardware. This allows for greater flexibility in implementing complex instructions.

5. Emphasis on high-level programming languages: CISC architectures are designed to support high-level programming languages, allowing complex operations to be expressed directly in the code. This can simplify programming and improve productivity.

Advantages of CISC architecture:
- CISC architectures can perform complex operations in a single instruction, reducing the number of instructions required to complete a task.
- CISC processors often have a large instruction set, providing a wide range of operations that can be performed directly by the hardware.
- CISC architectures are well-suited for high-level programming languages, allowing complex operations to be expressed directly in the code.

Disadvantages of CISC architecture:
- CISC architectures can be more complex and difficult to design and implement than simpler architectures, such as RISC (Reduced Instruction Set Computer).
- CISC processors often have longer instruction execution times compared to RISC processors, due to the complexity of the instructions.
- CISC architectures may require more memory to store the larger instruction set.

In conclusion, CISC stands for Complex Instruction Set Computer. It is a computer architecture that uses a large number of complex instructions to perform a wide range of operations. CISC architectures have advantages in terms of their ability to perform complex operations in a single instruction and support high-level programming languages, but they can be more complex to design and implement compared to simpler architectures.