What Makes the Engines Tick?

I started with a post on Houdini, Komodo, Stockfish and eventually reached Battering the Gruenfeld. Now I'd like to look a little deeper into the engines' internals. The best explanations that I've seen are found at chessprogramming.wikispaces.com, from which I took the following introductions.

Houdini:

A chess engine by Robert Houdart, which appeared in 2010 as closed source engine, free for non-commercial use. [...] According to its author, Houdini 3 applies a accelerated principal variation search, also dubbed "Smart" Fail-High. If a different move becomes best at very high search depths at the root, re-searches to determine its exact score and the new principal variation are done faster due to a reduced search depth, presumably in conjunction with extensions along the PV.

Komodo:

A chess engine by primary author Don Dailey and, since October 2013, by Mark Lefler, supported by chess advisor and evaluation expert and Don's long time collaborator Larry Kaufman. Komodo appeared in January 2010 derived from Don's former engine Doch. It uses bitboards as internal board representation, and has a sophisticated search and a knowledge based, balanced evaluation.

Stockfish:

A UCI compatible open source chess engine developed by Tord Romstad, Marco Costalba, and Joona Kiiski. Marco forked the project from version 2.1 of Tord's strong engine Glaurung, first announced by Marco in November 8, 2008 [1] . Starting out among the top twenty engines, it has quickly climbed in strength. The name "Stockfish" reflects the ancestry of the engine.

Now I have some serious reading to do. I'll come back to the subject when I understand more.