Crime can be cognizable or non-Cognizable. Difference between a cognizable and a non-cognizable offence is that in a non-cognizable offence the Police cannot arrest a person without orders of the court, i.e. without a Court warrant.
In a cognizable offense the police can take cognizance of the offence on its own i.e. it need not wait for the court orders as the law envisages that in such offences permission of the court to the police to investigate the crime is implicit.
In India, crimes like rape, murder, theft etc. are considered cognizable, and crimes like public nuisance, simple hurt, mischief etc. are considered non-cognizable.
The offences under 66A are cognizable: police authorities were empowered to arrest or investigate without warrants, based on charges brought under the Section. This resulted in a string of highly publicized arrests of citizens for posting objectionable content online, where the ‘objectionable’ contents were more often than not, dissenting political or innocuous personal opinions.