Use the link bellow, I think it's well developed.
Adjusting Entries, Accruals and Deferrals, ......
Good reading.
Adjusting entries and Accounting Principles
Adjusting entreis are tools by wich accountants apply the Realization and Matching Principles
Through these entries, revenues are recognized as they are earned, and expenses are recognized as ressources are used or consumed (used up) in producing the related revenue.
lets move now to another concpet, called the concept of materiality:
The concept of materiality allows accountants to use estimated amounts and to ignore certain accounting principles if these actions will not material effect on the financial statements. A material effect is one that might reasonably be expected to influence the decisions made by the users of financial statements.
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