Explore hierarchical component-based modeling using ModelingToolkit.jl in this comprehensive JuliaCon 2024 tutorial. Dive into the world of acausal modeling tools and learn how to build large-scale, high-fidelity models for simulating real-world phenomena such as hydraulic, HVAC, and multibody systems. Discover how ModelingToolkit, as the symbolic modeling layer of Julia's SciML, allows for reusable component-based modeling and automatic equation simplification. Learn to create steady-state models, transient models, and optimization models while leveraging the ModelingToolkitStandardLibrary for pre-built components. Explore the ecosystem surrounding ModelingToolkit, including graphical user interfaces, specialized solvers, and model analysis tools. Cover advanced topics such as moment closure expansions, file readers for importing models, MathOptInterface integrations for optimization, structural identifiability analysis, and linearization techniques.