Why is revenue recognition a significant issue? How do we determine when revenues are recorded for accounting purposes?

Income Statements
**Part I.
• Why is revenue recognition a significant issue? How do we determine when revenues are recorded for accounting purposes?
• Explain the difference between a product and period expense.
• Discuss the matching concept as it relates to accounting for revenues and inventory.

**Part II.  Refer to the latest annual financial statements for the two following companies: Apple: http://investor.apple.com/ and Samsung: http://www.samsung.com/us/aboutsamsung/ir/newsMain.do. Generally, this information is found in the Investor Relations area of the website.
Clearly identify the companies, the time period, and include the link to the financial statements you are analyzing in your report.
• What accounting conventions do the two companies follow, US GAAP or IFRS?
• Locate the income statement for the past two years for both companies. Prepare a table comparing five items or more from each statement.
• Comment on the changes from one year to another. Is the company doing better or worse? Did revenues and expenses increase or decrease?
• Is it easy to discern trends or compare the information from year to year and between the two companies? Please, comments on both aspects and show some examples.