Advanced+Spreadsheet+Functions

Task
Complete the following advanced spreadsheet functions:

Today

Now

AND / OR

IF

Nested IF

Count

Count IF

Write a blog post titled "Advanced Spreadsheet Functions". Use the post to explain the following advanced functions:
 * Today
 * Now
 * And
 * Or
 * If
 * Nested If
 * Count
 * CountIf

Each explanation should be accompanied by a screenshot example.