Changes in your business environment can create great opportunities for your organization. Changes in the environment can also cause significant threats.
Opportunities can come from new technologies that help you reach new customers, from new funding streams that allow you to invest in better equipment, and from changed government policies that open up new markets. Threats can include deregulation that exposes you to intensified competition; a shrinking market; or increases to interest rates, which can cause problems if your company is burdened by debt.
PEST Analysis is a simple and widely used tool that helps you analyze the Political, Economic, Sociocultural, and Technological changes in your business environment. This helps you understand the "big picture" forces of change that you're exposed to, and, from this, take advantage of the opportunities that they present.
PEST Analysis is often linked with SWOT however, the two tools have different areas of focus. PEST Analysis looks at "big picture" factors that might influence a decision, a market, or a potential new business. SWOT Analysis explores these factors at a business, product-line or product level.
These tools complement one another and are often used together.
Here is a great site that helps explain PEST Analysis: https://www.quickmba.com/strategy/pest/
What nuances do you see between PEST and SWOT and when, if any time, might be one tool be better utilized than another?