The stock market is a marketplace where investors buy and sell shares of publicly traded companies. In the UK, the main stock exchanges are the London Stock Exchange (LSE) and the Alternative Investment Market (AIM).

• London Stock Exchange (LSE): The LSE is one of the largest stock exchanges globally, where established, large-cap companies are listed. Investors can buy shares in these companies, meaning they own a small part of the business.
• Alternative Investment Market (AIM): AIM is a sub-market of the LSE, designed for smaller or emerging companies. It allows investors to invest in growing businesses that might carry more risk but also potential for higher returns.

Public Companies and Shares:

• Public Companies: These are businesses that have gone through an Initial Public Offering (IPO) to sell shares to the public. Once listed, their shares are traded on stock exchanges.
• Shares: A share represents a unit of ownership in a company. Shareholders can benefit through dividends (a share of profits) and capital appreciation (an increase in share price).

Indices:

• FTSE 100: This index tracks the 100 largest companies by market capitalization listed on the LSE, such as BP and HSBC. It is often seen as a barometer of the UK economy.
• FTSE 250: This index includes the next 250 largest companies after the FTSE 100. These mid-cap companies provide more growth opportunities but tend to be riskier than FTSE 100 stocks.

Together, these indices help investors gauge the overall performance of the UK stock market.