This lecture introduces the fundamentals of complex analysis, focusing on complex functions and their properties. The instructor begins by discussing the basic notations and definitions related to complex numbers, including the real and imaginary parts, and the concept of the complex conjugate. The lecture emphasizes the importance of the complex plane and how to represent complex numbers graphically. The instructor explains the polar and exponential forms of complex numbers, highlighting the relationships between these forms. The discussion then transitions to holomorphic functions, detailing the conditions for a function to be holomorphic, including the Cauchy-Riemann equations. The instructor provides examples to illustrate these concepts, demonstrating how to determine the continuity and differentiability of complex functions. The lecture concludes with a discussion on the applications of complex analysis, particularly in solving differential equations, and the significance of understanding these concepts for further studies in mathematics and engineering.