Pramana (Evidence) It refers to the means by which truth is checked.
Real knowledge or the actual happening is known as the prama or the truth whereas the means by which the truth is checked is known as pramana. In other words it can be said that pramana is the means that detects the difference between truth and lie, actual and virual.

Classification of Pramana

Charaka

• Pratyaksha
  
• Anumana
  
• Yukti
  
• Aptopdesha

Sushrata

• Prayiaksha
  
• Anuman
  
• Upamana
  
• Aptopdesha
  
• Pratyaksha

When the praman or the evidence is sensed or felt by the senses i.e. it is seen, smelled, touched by eye, hand, nose etc and then decided by the mind about what the substance really is.

Anuman
It is the anticipation of living beings i.e. the situation where the perceived knowledge is beyond the judgement of our senses we anticipate. Two important things are considered Lingi (matter) and Linga (property). By the means of Linga (property) Lingi is identified. Linga and Lingi has Samya relation (Intimate relation), which can be explained by the following example:

If a man smokes cigarette and the other man behind him is blind he can make out from its smell sense that it is the smoke of cigarette. Given the chance to pick up the same brand from cigarettes lying on table, the blind man will not be able to do so.

Yukti Praman
Made by Charaka this praman is considered to be a Anuman Praman. Yukti is the synonym of Yojna i.e. planning or intellectually planned. It is noteable that Anuman is made by the means of Yukti and this is when it is considered as Yukti Parman.

Upman Praman
It is named by Shushrutu. It is the situation in, which one very well known thing is compared to other less known thing as result of some degree of similarity that exists between the two. The example is of diseases like Danustambha (bow like disease) in ayurveda that is named so because in this type of disease the body tends to bend like a Dhanusha (bow).

Aptopdesha
It refers to a knowledgeable person whose words are regarded as Apta Vachan. Most of the updeshas contain these sacred informative words or the Apta Vachan. The books that carry such words are called Aptopdesha and the knowledge received is Aptopdesh Praman.