Salesforce has a bunch of rules that can be defined on objects and fields. For example, you can define validation rules, workflow rules, process builder, flows, assignment rules, escalation rules, auto-response rules, triggers etc.
Whether you are an administrator, consultant, developer, or architect – it is important for you to understand the order in which these rules and triggers are executed.
The following picture depicts the order of execution visually. (For finer details, please refer to the Apex Developer Guide URL mentioned under ‘References & Useful URLs‘ section below).