The boards on this site stand on work other people gave away. Here is who made what.
cm-chessboard by Stefan Haack, under the MIT license. It draws the board and takes your move by mouse or finger.
chess.js by Jeff Hlywa, under the BSD 2-Clause license. It knows the rules, what is legal and what the position looks like after your move.
The piece drawings come from Wikimedia Commons, drawn by Colin M. L. Burnett and Rfc1394, and adapted by Stefan Haack for cm-chessboard, under CC BY-SA 3.0. If you have played chess online, you have seen them. They are the same set lichess and half the internet use.
Our videos and slides may show a 3D chess set. Other people made it and shared it.
“A Beautiful Game” © 2020 ASWF, original assets by Moeen Sayed and Mujtaba Sayed for SideFX; glTF conversion © 2022 Ed Mackey; CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)
The model and its license live in Khronos glTF Sample Assets
How often a move gets played, and how the players who choose it score, come from the Lichess opening explorer. Where a number on the site names a rating band, the band is stated with it. Lichess publishes its data under CC0, so no permission is needed and none was asked. Positions are checked with python-chess before they reach a page.