A museum is a "permanent institution in the service of society and of its development, open to the public, which acquires, conserves, researches, communicates and exhibits the tangible and intangible heritage of humanity and its environment, for the purposes of education, study, and enjoyment", as defined by the International Council of Museums.The UK Museums Association definition (adopted 1998) is:
“ Museums enable people to explore collections for inspiration, learning and enjoyment. They are institutions that collect, safeguard and make accessible artifacts and specimens, which they hold in trust for society.”

Museums collect and care for objects of scientific, artistic, or historical importance and make them available for public viewing through exhibits that may be permanent or temporary. Most large museums are located in major cities throughout the world and more local ones exist in smaller cities, towns and even the countryside. Many museums offer programs and activities for a range of audiences, including adults, children, and families, as well as those for more specific professions. Programs for the public may consist of lectures or tutorials by the museum faculty or field experts, films, musical or dance performances, and technology demonstrations. Many times, museums concentrate on the host region's culture. Although most museums do not allow physical contact with the associated artifacts, there are some that are interactive and encourage a more hands-on approach. Modern trends in museology have broadened the range of subject matter and introduced many interactive exhibits, which give the public the opportunity to make choices and engage in activities that may vary the experience from person to person. With the advent of the internet, there are growing numbers of virtual exhibits, i.e. web versions of exhibits showing images and playing recorded sound.

Museums are usually open to the general public, sometimes charging an admission fee. Some museums are publicly funded and have free entrance, either permanently or on special days, e.g. once per week or year.

Museums are usually not run for the purpose of making a profit, unlike private galleries which more often engage in the sale of objects. There are governmental museums, non-governmental or non-profit museums, and privately owned or family museums. Museums can be a great source of information about cultures and history.

Source : www.wikipedia.org