If you are looking for open datasets for your study, assignment, presentation, or application design and development these are some of the resources you can use.
You can also use some of these repositories to archive your data (see Repositories for Research Data)
General Data Search Engines and Registries
DataCite - helps locate, identify, and cite research data
DoltHub - A community for data collaboration
General Repositories for Research Data
Academic Torrents - a distributed system for sharing big datasets
Subject Specific Repositories for Data
UCI Machine Learning Data Repository maintains hundreds of data sets as a service to the machine learning community.
OpenML - offers datasets and performance measures and feedback for machine learning algorithms
ICPSR archive maintains datasets of research in the social and behavioral sciences
Opportunity Insights - data on income inequality, social mobility, college attendance, life expectancy and more
IEEEDataPort - IEEE backed data repository that provides access to thousands of datasets
AI Communities and Model Repositories