In-Memory Processing Architectures and Applications, published as Volume 144 of the serial Advances in Computers, provides a comprehensive and up‑to‑date examination of processing‑in‑memory (PIM) and compute‑in‑memory (CIM) architectures, addressing their architectural foundations, circuit‑level innovations, security and reliability challenges, and emerging application domains. This volume brings together authoritative contributions that span DRAM‑ and SRAM‑based in‑memory computing, ferroelectric and other emerging memory technologies, modelling and simulation frameworks, and system‑level interconnect innovations, offering a balanced perspective on both the promises and pitfalls of PIM. Collectively, the chapters position in‑memory processing as a key enabler for overcoming data‑movement bottlenecks in modern computing systems while highlighting the reliability, energy efficiency, scalability, and security considerations that must be addressed for real‑world deployment.