This paper offers a comprehensive introduction to Bayesian inference, combining historical context, theoretical foundations, and core analytical examples. Beginning with Bayes' theorem and the philosophical distinctions between Bayesian and frequentist approaches, we develop the inferential framework for estimation, interval construction, hypothesis testing, and prediction. Through canonical models, we illustrate how prior information and observed data are formally integrated to yield posterior distributions. We also explore key concepts including loss functions, credible intervals, Bayes factors, identifiability, and asymptotic behavior. While emphasizing analytical tractability in classical settings, we outline modern extensions that rely on simulation-based methods and discuss challenges related to prior specification and model evaluation. Though focused on foundational ideas, this paper sets the stage for applying Bayesian methods in contemporary domains such as hierarchical modeling, nonparametrics, and structured applications in time series, spatial data, networks, and political science. The goal is to provide a rigorous yet accessible entry point for students and researchers seeking to adopt a Bayesian perspective in statistical practice.