An NRI is an Indian citizen who stays outside India.
a. For purposes of carrying out employment or any business or vocation.
b. Under circumstances indicating an intention to stay outside India for an uncertain duration.

Any Indian citizen deputed outside India for a temporary period in connection with employment.

A citizen of a foreign country (other than a citizen of Bangladesh or Pakistan) is a PIO.

Any NRI/PIO can open two types of savings accounts with any bank in India. They are NRE and NRO bank accounts.

A NRE bank account is an external saving bank account opened for Non resident Indians. This is why it is known as Non-Resident External account. Since it is an external account, any monies lying in NRE account can be taken outside the country or in other words, the monies lying in NRE account are fully repatriable. This money can be converted into any foreign currency at the behest of the account holder and can be remitted outside the country.

A NRO bank account is an ordinary saving bank account opened for Non resident Indians. This is why it is known as Non-Resident Ordinary account. Since it is an ordinary account i.e. as good as a normal saving bank account, monies lying in NRO account cannot be taken outside the country or in other words, the monies lying in NRO account are not repatriable.

Yes money can be freely transferred from NRE account to NRO account.

No, money cannot be transferred from NRO account to NRE account.

RBI has advised banks to re-designate such accounts as resident accounts on return of the account holder to India.

As per section 6(5) of FEMA, NRI can continue to hold the securities, which he/she had purchased as a resident Indian, even after he/she has become a non-resident Indian, but has to transfer the shares to his NRO (Non Resident Ordinary) account

NRIs are permitted to make direct investments in shares/ debentures of Indian companies/ units of mutual fund. They are also permitted to make portfolio investments i.e . purchase of share / debentures of Indian Companies through stock exchange. These facilities are granted both on repatriation and non-repatriation basis.