Online Chess Databases

Online Chess Database Resources

 365Chess.com Chess Database

Claims to be the biggest Chess Database online. ECO Openings index and Openings Explorer. To Download games you must sign up with site. (Registration is Free) 365Chess Database - 3.5 Million Game Database 

Lichess Openings Explorer 

- let you search through over 12 million Lichess games (and counting!) with more than 390 million unique positions, but it also features a specially curated database of 2 million master games from thousands of over-the-board tournaments since 1952! That's right, a fully featured opening explorer is now a part of lichess.org and it's all completely free!

ChessGames.com 

- This Link is to 3500 Annotated games.

ChessGames.com Opening Explorer 

- Database of several Million Games

Chess Tempo Database

-  provides over two million searchable chess games. The database can be searched via many criteria, including chess players, chess opening, player ratings, game result, and the year the chess game was played. 

Chess Training Page

Chess.com -Chock full of Free Beginner lessons.

 

Lichess Learn -  Lichess (Everything here is free) fill of videos, interactive lessons and study plans.

Here is a list of over 130 Chess lessons and tutorials in PDF and HTML format all in one place gathered from all over the Internet.
Chess Tutorials

Predator at the Chessboard - A field guide to chess tactics. Lots of Lessons on tactics with practical examples and quiz's. This is a really nice free site for anyone wanting to improve their tactics.

Beginner Lessons
Chesskid.com  -  Offers Instruction to help Kids learn Chess (Lessons and Videos Very nice)
Chess Lab  - Basics are covered
US Chess Federation Beginner Course
Chess Corner Learn Chess Guide - Bunch of Very nice lessons right up to intermediate stuff.

Chess Tactics Servers

Chess Tactics Resources 

Here are a couple servers that dish up chess problems that you solve with differing degrees of difficulty. You must set up an account on each but they are free.

LiStudy

-  Pretty Amazing Site for Tactics and just plain chess Training.

Tactics Problems,  Blind Tactics Problems (Have not seen this anywhere else for help with Visualization) Piece-less tactics problems as well.  
Openings - study with spaced repetition like Chessable. 
Endgames - Pick an endgame and practice against Stockfish.
Unlimited and Free

Lichess Puzzles

 - ( Hands Down one of the Best ) Amazing place to train tactics, keeps track of each type of tactic you do and can train just weaknesses if you so desire. Unlimited and FREE.

Now also has Tactics Broken Down into  (Pick your Poison)

Mates  (14 Types Listed here)
Different types of Mates - Mate in 1 thru Mate in 5 
Different Types of Mating Patterns - Back-rank, Anastasia,Greco, etc.

Openings ( 115 Openings Listed w/ Over 1000 Variations here)
All the Openings and all the Sub variations from each opening

Different Phases of the game  to different Types of Endgames.

Motifs -  Fork, Pin , Double Check etc.  (14 Motifs Listed)
Advanced Motifs - Attraction , Intermezzo, X-Ray etc.  (9 Advanced Motifs)
Lengths - One-Move, Short, Long, Very long Puzzle
Origins  - Player games, Master games, Super GM Games,  Master vs Master

Chess Tempo

 also gives you a rating for solving problems and has a lot to do for free as well. 32,000 + problems here and in all honesty this site is a lot nicer looking and will give you things like the average time a problem was completed, the type of problem, along with graphs and such of your performance.
There are two ratings given here, one for Blitz (Problems with a time limit) and Standard (Just solving with no time limit) The comments section here is a lot of help as well for figuring out why a problem is solved a certain way.
This site now offers endgame problems as well with an Endgame Rating.

 

Ideachess

 - Signup is Free. Unlimited amount of Tactics and Mate Puzzles a Day. They give you a ELO Tactics rating as you do puzzles and you can see where your ranked on the site compared to everyone else. Problems for all from Beginner, intermediate to advanced. (Can go in and practice on problems and pick the ones you want )

 

If you like just working on your tactical awareness while looking at the board these places are for you.

Chess.com Tactics Trainer 

- If you sign up for a free account you can use their tactics trainer for 3 timed problems a day. This site gives you a tactics rating as well.I have to say the problems here appear to be really very good.

365Chess Tactics Trainer

-  Basic Members Can do 25 Puzzles a day.  Gives you a puzzle rating on how you do. Can pick to do puzzles from Real Games or Chess Compositions.

ChessGym 

-  another Very Nice site with over 60,000 rated problems. Sign up for a free account. Can do Blitz, Endgame, Attacking, Defending.