There are many sources of free data available across a variety of topics, such as weather, population, and geographical data. Here are some notable examples:

### Weather Data 1. **OpenWeatherMap**: Provides current weather data, forecasts, and historical data. Free tier available with limited calls. - [OpenWeatherMap](https://openweathermap.org/) 2. **WeatherAPI**: Offers weather data including forecasts and historical data. - [WeatherAPI](https://www.weatherapi.com/) 3. **National Weather Service (NWS)**: Provides weather, water, and climate data. - [NWS](https://www.weather.gov/) ### Population Data 1. **World Bank Open Data**: Comprehensive datasets on global development, including population statistics. - [World Bank Open Data](https://data.worldbank.org/) 2. **United Nations (UN) Data**: Offers a wide range of statistical data, including population demographics. - [UN Data](http://data.un.org/) 3. **U.S. Census Bureau**: Provides extensive population data for the United States. - [U.S. Census Bureau](https://www.census.gov/data.html) ### Geographical Data 1. **OpenStreetMap (OSM)**: A collaborative project to create a free editable map of the world. - [OpenStreetMap](https://www.openstreetmap.org/) 2. **Natural Earth Data**: Public domain map datasets available at various scales. - [Natural Earth Data](https://www.naturalearthdata.com/) 3. **NASA Earth Observing System Data and Information System (EOSDIS)**: Provides satellite imagery and data on Earth's systems. - [NASA EOSDIS](https://earthdata.nasa.gov/) ### Additional Resources 1. **Google Dataset Search**: A tool for finding datasets across the web. - [Google Dataset Search](https://datasetsearch.research.google.com/) 2. **Kaggle Datasets**: A variety of datasets uploaded by the community, often used for machine learning and data science projects. - [Kaggle Datasets](https://www.kaggle.com/datasets) 3. **Data.gov**: The U.S. government's open data portal, providing datasets across various domains. - [Data.gov](https://www.data.gov/) 4. **European Union Open Data Portal**: Provides access to datasets from various EU institutions and agencies. - [EU Open Data Portal](https://data.europa.eu/euodp/en/data/) 5. **World Health Organization (WHO) Data**: Health-related data, including statistics on diseases, health indicators, and more. - [WHO Data](https://www.who.int/data) These sources provide a wealth of free data that can be used for research, analysis, and application development. Make sure to check the usage terms and conditions for each dataset, as they can vary.