These are both great sites that I would recommend to everyone. You can play games on both sites (both correspondence and live), but there are also many useful resources and training tools on both sites. chess.com has many free features, but some that you have to pay for, although it is well worth the money. lichess has slightly less features but is free to all. One highly useful tool is tactics, called tactics trainer on chess.com, and training on lichess. You are given puzzles to solve in both cases and are timed and rated. The puzzles then adjust to your level of play. On chess.com you can do 5 tactics a day as a free member. There are over 1000 highly instructive videos on chess.com too. Most of these are for paid member only, but some are free, and there is a crash course for beginner which is free to all: part 1 part 2 part 3 part 4 part 5 There is also Chess Mentor and Computer workout which are great for learning new ideas and practising certain positions against the computer. Both sites also have analysis boards that allow you to analyse certain positions, or view games you have saved/downloaded as a PGN file.
Youtube also has loads of chess videos for you to explore, some of which are linked on the lichess site under videos.
There are loads of good chess books out there for all levels, and there a re even a few in the UCC library. Below is just a small handful:
Let’s Play Chess: A Step-By-Step Guide For New Players (by Bruce Pandolfini) : A good book for beginners that starts from the basics and covers some of the main strategies/tactics used in chess.
Silman’s Complete Endgame Course: From Beginner To Master (by Jeremy Silman) : An absolutely fantastic book for players of all level. It covers essential endgame knowledge, and is broken down into different sections for players of different levels. It starts at the novice level and goes all the way up to master level. As you improve as a player you can keep coming back to this book to new information.
Winning Chess Tactics (by Yasser Seirawen with Jeremy Silman) : Another great book that focuses on solely on tactics, arguably the most important aspect of chess. Almost all games below a very high level are decided by tactics, so needless to say they are very important.
Winning Chess Strategies (by Yasser Seirawen with Jeremy Silman) : Another great book in the same series as the above one. Teaches you about various different kind of strategies that are used in chess, and will help you to come up with a long term plan in your games.
My 60 Memorable Games (by Bobby Fisher) : An absolute must-read for chess players of all levels. This universal book, written by one of the greatest players ever to play the game, gives a rare glimpse into his mind. Fisher goes over, and critiques 60 of his games, which includes 3 of his losses, and a number of draws.