1) Shares represent ownership in a company, with each share representing a unit of the company's total share capital. Share capital is the total funds raised by a company through the issue and sale of shares.
2) There are two main types of shares - preference shares and equity shares. Preference shares carry preferential rights to dividends and repayment of capital. Equity shares do not have preferential rights.
3) Within preference shares, there are various sub-types including cumulative, non-cumulative, participating, convertible, and redeemable preference shares. Equity shares represent the residual claim on a company's assets and earnings.