Is Sentinel satellite data free?

Excuse me, could you please clarify if the Sentinel satellite data is freely accessible to the public? I've heard conflicting information on this matter, and I'm interested in using it for a project I'm working on. Is there any cost associated with downloading or accessing this data, or is it completely free of charge? Additionally, are there any restrictions or limitations on how this data can be used? I'd appreciate any information you can provide to help me understand the accessibility and usage of Sentinel satellite data.