【中文版】

投行是指投资银行，是专门从事证券发行、承销、交易、企业重组、兼并与收购、投资分析等业务的金融机构。它与传统的商业银行不同，投行不吸收存款，不发放贷款，而是为资本市场提供各种金融服务。

投行的主要业务包括证券承销、证券交易、企业融资、并购重组等。证券承销是投行的基本业务之一，它包括帮助公司发行股票、债券等证券，也包括协助公司进行证券私募和定向发行。证券交易是投行的核心业务之一，它涵盖了股票、债券、衍生品等多种金融工具的交易。企业融资是投行为企业提供的金融服务之一，它包括股权融资、债权融资等多种形式。并购重组是投行为企业提供的另一种服务，它帮助企业进行兼并、收购、重组等业务。

投行在金融市场上扮演着重要的角色。它是连接资本市场和实体经济的桥梁，通过为投资者和企业提供各种金融服务，促进了资本的流动和经济的发展。同时，投行也是金融创新的重要推动力量，它不断推出新的金融产品和服务，满足了投资者和企业不断变化的需求。

总的来说，投行是一个提供各种金融服务的金融机构，它为资本市场的发展和实体经济的繁荣做出了重要的贡献。

【英文版】

Investment banking (IB) refers to the professional financial services provided by banks and other financial institutions to help companies launch securities, engage in mergers and acquisitions, and provide advice on corporate strategies and capital operations. IB plays a crucial role in the global capital market and corporate finance, connecting the capital markets with the real economy.

The main businesses of IB include underwriting securities, trading securities, corporate finance, mergers and acquisitions, and investment advice. Underwriting securities involves assisting companies in issuing stocks, bonds, and other securities, as well as assisting companies in private placements and directed issuances. Trading securities involves buying and selling stocks, bonds, derivatives, and other financial instruments. Corporate finance involves providing advice and services to help companies raise funds, manage debt, and optimize capital structures. Mergers and acquisitions involve assisting companies in mergers, acquisitions, and restructuring.

Investment banking plays a crucial role in the global economy. It serves as a bridge between the capital markets and the real economy, facilitating capital flows and promoting economic development by providing various financial services to investors and companies. It is also a key driver of financial innovation as it continuously develops new financial products and services to meet the changing needs of investors and companies.

In summary, investment banking is a crucial component of the global economy that provides various financial services and plays a vital role in capital market development and economic prosperity.