When a company is acquired, what does open offer mean?

A joint stock company is acquired by acquiring the
majority shares or stocks of the company. This can be done by purchasing the shares
using normal stock exchange facilities, or private transactions between the buyer and
sellers. Another route of acquiring majority shares is to make a offer, through a public
announcement, to all existing shareholders of the company to sell their shares at a
fixed price. This offer made to the general public to buy their shares is called "open
offer".

A company or a person may make open public offer
for purchase of shares of a company to acquire controlling interest in the company, or
just to increase their holding.

Some countries have laws
that require a person or company to make public offer under certain conditions. For
example, in India a public offer for purchase of share becomes mandatory when the market
or private purchase of shares results in total holdings of purchaser crosses a threshold
level in terms of percentage of total shares of the company.