Lesson 6: Bar with Option...or Option with Bar?

Topic 1: What is Option Bar?
Option bar controls contextualized options for different tools present . It also contains work space menu, where we can save and load arrangements of palettes.
Topic 2:Some Examples of Option bar:

Tools with their own Option bar
Move tool
Magic wand tool
Crop tool
Brush tool
Paint Bucket tool
Gradient tool
Rectangle tool
Text tool

Source: