You should not read this post. It describes a bad practice.
Calculated fields are fields that do not have their own values, but the values are calculated from the other fields of the same record. It is easiest to implement them in Model.
Knowing the phases of component life cycle is important for every developer. Learn what the phases are and what is happening in each of them.
Event are often misunderstood as to their origin, purpose and handling. You can find in-depth definition of events which knowledge gives you the potential ability to effectively use them in your applications whether small or large.