This Open Data Portal provides many ways to search, filter and preview our GIS data before you download it.
Once you find what you need, you can simply click on the link "Open in ArcGIS" to open the data layer in ArcGIS Online.
You can add multiple data sources there, style it, and print your map! (However, if you want to save your map you'll need to create your own free public account with ArcGIS Online.)
Advanced User Information
For advanced users, under "Download Datasets" there are more ways for you to download the data to your computer, including:
KMLs
Shapefiles
Spreadsheets
Programmers
For the programmers out there, under "APIs" there are links to our live data so you can use it to enrich your web applications, including:
GeoJSON
Map Services (GeoService)
Data Details
While browsing the open data sources, make sure to read the data layer's "Description" which explains the data contents. Each data layer also has a "Metadata" link which explains in detail the contents of the data table. Learning what the data means makes the data more useful to you and the people you share the data with!