Windfall Tax is a type of tax levied by the government on specific industries that experience a sharp increase in revenue. It serves as a supplementary revenue stream for the government. Both of these statements are correct.

Explanation:

1. Windfall Tax:
A windfall tax is a tax imposed by the government on industries or businesses that generate unexpectedly large profits or experience a sudden increase in revenue. This tax is usually levied on specific sectors or industries that are deemed to have received an undeserved windfall gain. The purpose of the tax is to redistribute the excess profits earned by these industries back to the government or to other sectors of the economy.

2. Higher Tax on Specific Industries:
Windfall taxes are typically imposed on industries that are perceived to have benefited from external factors beyond their control, such as favorable market conditions, natural resource discoveries, or government policies. These industries often experience a sudden surge in revenue, leading to higher profits. By imposing a higher tax on these industries, the government aims to capture a portion of these windfall gains and use them for various purposes, such as funding public services, infrastructure development, or reducing budget deficits.

3. Supplementary Revenue Stream:
Windfall taxes serve as a supplementary revenue stream for the government. They provide an additional source of income that can supplement the government's regular tax revenues. This extra revenue can be used to fund various government programs and initiatives without relying solely on the regular tax collection. It helps diversify the government's revenue sources and reduces dependence on specific sectors or taxpayers.

4. Advantages and Disadvantages:
Proponents of windfall taxes argue that they promote fairness and equity by ensuring that industries that benefit disproportionately from unforeseen circumstances contribute their fair share to society. It also helps prevent excessive concentration of wealth and income disparities. However, critics argue that windfall taxes can discourage investment and innovation in the affected industries, potentially leading to negative economic consequences.

In conclusion, windfall taxes are higher taxes levied by the government on specific industries that experience a sharp increase in revenue. They serve as a supplementary revenue stream for the government, providing an additional source of income to fund public services and reduce budget deficits.