EBIT, or earnings before interest and taxes, is a measure of a company's profitability that excludes the cost of financing and taxes. It is calculated by taking a company's revenue and subtracting its operating expenses, such as cost of goods sold, selling and administrative expenses, and research and development expenses. EBIT is useful for comparing a company's profitability to its industry peers and for analyzing the efficiency of its operations.

EBITDA, or earnings before interest, taxes, depreciation, and amortization, is a measure of a company's profitability that excludes the impact of non-cash expenses, such as depreciation and amortization. It is calculated by taking a company's EBIT and adding back these non-cash expenses. EBITDA is often used as a proxy for a company's cash flow, as it excludes the effects of financing and taxes and focuses on the company's underlying operating performance.

Profit after tax, or net income, is a measure of a company's profitability that reflects the impact of all expenses, including financing and taxes. It is calculated by taking a company's revenue and subtracting all expenses, including cost of goods sold, selling and administrative expenses, research and development expenses, interest expense, and taxes. Profit after tax is the bottom line measure of a company's profitability and is often the most closely watched by investors and analysts.

In summary, EBIT, EBITDA, and profit after tax are all important metrics for evaluating a company's financial performance and profitability. EBIT measures a company's profitability excluding the cost of financing, while EBITDA excludes the impact of non-cash expenses such as depreciation and amortization. Profit after tax, or net income, reflects the full impact of all expenses and is the final measure of a company's profitability. Understanding these metrics can help investors, analysts, and business owners make informed decisions about a company's financial health and success.