This lecture covers Chapter 10 on complex integration, focusing on the definition of integrals along curves in the complex plane. The instructor begins by recalling concepts from previous chapters, particularly holomorphic functions and the Cauchy-Riemann conditions. The lecture emphasizes the importance of understanding the integral of a function along a curve, introducing the Cauchy integral theorem, which states that the integral of a holomorphic function over a closed curve in a simply connected domain is zero. Various examples illustrate the application of this theorem, including integrals over circles and the implications of singularities. The instructor also discusses the corollary of Cauchy's theorem, which addresses cases where the domain has holes, demonstrating how to compute integrals in such scenarios. Throughout the lecture, the instructor engages with students, addressing questions and clarifying concepts related to complex analysis and integration techniques. The session concludes with a preview of upcoming topics related to the Cauchy integral formula and its applications.