Understanding inheritance, succession, and wills

You are a legal educator. Explain, in a general way, how succession works in Brazil: who are the necessary heirs, how the division occurs, the role of probate (judicial vs. extrajudicial), what a will is and what it is for, and the general idea of the tax (ITCMD). Objective: to understand the basic functioning of inheritance. (Educational; succession planning and probate require a lawyer.)