It was the first fully-featured chess engine released under a Free software licence. Like all other chess engines, Houdini uses alpha-beta search. As with all chess engines, Houdini uses a time-tested opening database and a time-tested move generation algorithm. Houdini has an extensive analysis library, so its opening variations are analysed very deeply, with a move-by-move visualization in the Houdini GUI.
History
Houdini was initially written as a hobby project in 1999, and was only released in 2006. It is widely regarded as the best chess engine available.
In 2007, Houdini was first placed in the Top 10 Chess Computers Category in the World Chess Federation (FIDE) World Computer Chess Championship, held in Taipei, Taiwan, in January 2007.
In 2008, Houdini was ranked #3 out of the Top 10 Chess Computers category in FIDE World Computer Chess Championship, held in Batumi, Georgia. In the 2009 tournament, Houdini placed #4 out of the Top 10. The 2010 edition placed Houdini at #8.
In August 2011, Houdini was the highest ranked engine in the free ChessBase version of the tournament, scoring 7.5/9, making it the highest ranked engine in all of ChessBase.
In August 2012, Houdini scored 8.5/9 in the ChessBase tournament, winning the first place in this section and in overall ranking.
In December 2012, Houdini won the World Computer Chess Championship at the 15th European Games.
In January 2013, Houdini achieved a stunning victory in the first round of the 6th edition of the US Open Computer Chess Championship.
On April 9, 2013, Houdini became the first chess engine to pass the TCEC "Grandmaster" (G/50) benchmark. It has achieved this milestone both in chess engines with the aim to "beat a real human" and in the TCEC computer chess tournament.
In December 2013, Houdini won the World Computer Chess Championship at the 15th European Games.
In January 2014, Houdini achieved a remarkable result at the first round of the first US Open Computer Chess Championship.
In May 2014, Houdini won the World Computer Chess Championship for the second time in a row.
The Houdini team also took part in the "Computer Chess Challenge" series of 3125841983
Related

Houdini 2.0c UCI Chess Engine Full Version ((FREE))