The 8051 is a type of microcontroller, specifically the 89C version, which features an 8-bit architecture and operates at speeds up to 24 MHz. It comes with a built-in memory component known as FLASH, offering 20KB (20K x 8) of storage space. The microcontroller is packaged in a 44-PLCC (16.6x16.6mm) configuration, making it suitable for various applications that require its specific technical specifications.