From latin observatĭo, the observation is the action and the effect to observe (look carefully, watch accurately, see). It is an activity carried out by human beings living in order to detect and assimilate any information. The term also includes the register of certain facts/events using instruments.
The observation is part of the scientific method. In fact, as experimentation, it allows the empirical verification of phenomena. Most science have recourse to observation and experimentation in a complementary manner.
Astronomy is often mentioned as an example of science based on observation. In this case, experimentation is not possible since the object of study cannot be transported to a laboratory.
Scientific observation is to measure/consider and take note of observable facts. This activity should take place objectively, without opinions, feelings and emotions have influence on scientific work.
After observation, the scientist must develop a hypothesis as explanation attempt of the observed phenomenon. The following steps of the scientific method the prediction (since it is a logical consequence of observation). Then, he made the experiences from these ideas. Finally, the scientist is able to reach a conclusion and, thus, contribute to the knowledge.
The observation also takes place in the field of art and is to look in detail in order to determine the characteristics of a work. When looking carefully at a work of art, we arrive to analyse the Visual qualities and to understand the meaning of what the artist wanted to express.