Learning how to play piano is not an extremely difficult task that has stringent age requirements, contrary to what some people think. Although there are advantages to learning at a young age, the piano is an instrument that can be mastered by anyone with the guts to persevere. The first requirement to learning this instrument is owning or having access to a piano.
Because the piano is a large and expensive piece of equipment, having a smaller and less expensive keyboard is a decent substitute for beginners. The main difference between these two instruments is that the keyboard has 66 keys, while the piano has 88 keys. Another important difference is that the piano keys are larger and heavier, making it more difficult to play for beginners.
This is an instrument that has been around for several hundred years and has been the subject of much study over the years, out of which many different methods for learning and teaching this instrument have emerged. Several people adopt the "learn by ear" method, which is where they simply fiddle and learn by trial and error. This method is rather ineffective and several bad habits can be acquired by attempting such a task without a proper tutor or instructor. In order to learn how to play the piano properly, a tutor of some sort is required. This can take the form of online video tutorials, DVDs, books or an actual teacher.
Those who are quick learners and have a lot of motivation will find that videos and books are very effective instructors and will be able to learn many different chords and even a little musical theory. A private teacher is generally considered more effective, as the teacher can modify the syllabus to suit the pupil's strengths and interest. Attending a music school also affords one the opportunity to learn musical theory (sheet music) properly.
The act of reading sheet music is a complex task, which takes some study, a little instruction and a lot of practice. Learning how to read sheet music enables one to be able to play complex compositions almost instantly, rather than trying to figure them out by ear. That being said, "Ear training", or learning to recognize musical intervals and tonal changes is a very important skill which is also taught by professional teachers. Once a method for learning has been appropriated, the next and most important element is practice. Skill and proficiency at this instrument is not absorbed and can only be achieved by steady and faithful practice. Learning how to play piano is something that can be achieved by a person of any age. The important thing is to choose an appropriate learning method on how to play piano and dedicates enough time to practice regularly.