The best place to start for a general introduction (including algorithms) is Reinforcement Learning: An Introduction by Sutton & Barto [0]. Another good one, focusing more on the algorithms is Algorithms of Reinforcement Learning by Szepesva [1]. Both are available for free online in PDF, see the links.

[0] http://incompleteideas.net/book/the-book-2nd.html

[1] https://sites.ualberta.ca/~szepesva/rlbook.html

The best place to start for a general introduction (including algorithms) is Reinforcement Learning: An Introduction by Sutton & Barto. Another good one, focusing more on the algorithms is Algorithms of Reinforcement Learning by Szepesva. Both are available for free online in PDF, see the links.