Closely held company definition under income tax act

Can you give me plain English definitions for the following: (1) a closely held corporation, (2) a personal holding company, and (3) a personal service corporation?

Generally, a closely held corporation is a corporation that:

A closely held corporation is subject to additional limitations in the tax treatment of items such as passive activity losses, at-risk rules, and compensation paid to corporate officers.

Refer to Publication 542, Corporations for more information.

Personal Holding Company

A corporation will be considered a personal holding company if it meets both the Income Test and the Stock Ownership Test.

Personal Service Corporation

Generally, the testing period for any tax year is the prior tax year. If the corporation has just been formed, the testing period begins on the first day of its tax year and ends on the earlier of:

A. The last day of its tax year, or
B. The last day of the calendar year in which its tax year begins.

Refer to Publication 542 for more information.