This document summarizes various data communication schemes used in wireless sensor networks (WSNs). It discusses key issues in WSNs like energy efficiency, data aggregation, and network lifetime. It then summarizes several common routing protocols used in WSNs to address these issues, including LEACH, PEGASIS, HEED, DEEC, TEEN, and SEP. LEACH uses randomized clustering to distribute energy load among sensors. PEGASIS forms chains to reduce transmissions. HEED allows energy-aware cluster head selection. DEEC handles heterogeneity. TEEN and SEP aim to improve responsiveness and support multi-level heterogeneity. The document concludes with a brief introduction to using fuzzy logic in WSN routing