Piano Chords, along with the piano scales, are the basic building blocks of most piano music. Learning the chords develops your keyboard awareness, and enhances your understanding of the music you read, memorize, compose, or improvise. You can get to know these basic building blocks by making them a part of your regular practice routine.
Once you have become familiar with the 12 major triads and the 12 minor triads in root position, you can begin learning how to invert them, voice them differently, spread them out, use them in melodies, and create accompaniment patterns with them. You will also find the triads handy for analyzing piano pieces you might be reading or memorizing. Thus the process of learning how to play the music (and memorize it) becomes much easier than if you had no such knowledge of chords.
The first chords a pianist should learn are the Major Triads and the Minor Triads. ("Triad" refers to a 3-note chord.) I've found that the best way for beginning students to learn these chords is by grouping them according to their appearance on the keys,or what I call their "keyboard image".
Once you've learned the chords in these groups, the next step is to play them chromatically: up and down in half-steps. Thus, you will find the same major and minor triads listed in half steps if you go to "Major & Minor Triads".
Once you know these triads in root position and can play them proficiently up and down in half-steps for at least one octave, try playing them around the circle of 4ths. This will not only increase your knowledge and feel for each chord, but will improve your keyboard awareness.
To learn more about developing keyboard awareness, go from "Piano Chords" to "Free Piano Lessons".
The diminished triads are also handy to know.
To see the diminished triads, listed chromatically, go to "Diminished Chords".