Every crime has four general stages:
Intention is the first stage in commission to an offence. Mere intention is not enough to suffice for a crime and thus mere intention is not punishable, Mere intention not followed by preparation, attempt or act cannot constitute an offence. The will cannot be taken for the deed, unless there is some external act showing progress in the direction of the crime. Intention can only be proved by acts. But once the act is done, the law judges not only the commission of the act, but also the intention with which the act was committed. Hence where a person is charged for doing an act, it is open to a Court of law to draw an inference of his intention for doing such an act. Thus if X intends to kill Y but does nothing in the direction of doing so; X cannot be punished. On the other hand, if for the purpose of killing Y, X purchases a revolver, tries to kill Y by aiming and firing at him, and thus killing him; the law in this case will take into account even the intention of X to kill why and punish him accordingly.
Preparation consists of devising or arranging means or measures for commission of an offence. It is thus a step further in the direction of committing the offence. Thus, in the above example, if X purchased the revolver and kept it with him, it amounts to preparation on his part to kill Y. Mere Preparation, however is not punishable. If X had a valid license to keep the revolver, he cannot be punished for any offence. It is said that it is possible that before a person goes beyond the stage of preparation and enters the third stage of attempt, he may give up the idea of committing the offence. Further, it is not necessary that a person making a preparation for committing an offence will always commit an offence. The law, thus allows an opportunity to repent(Locus Penitentiae) and does not punish the preparer unless he goes beyond the stage of preparation. However, under the IPC preparation of certain types are considered as grave offences which are punishable under the law such as Preparation for waging war against the government (Section 122), Preparation for committing dacoity (Section 399), etc.
Attempt is an endeavour to commit a crime. The term attempt is however, not defined in the IPC. Though Section 511 does not define attempt, it proved the punishment for attempt to commit an offence. Attempt can be broadly defined as an intentional act done by a person in the direction of committing an offence which failed in its object independent of the volition of the person doing it. It is thus a futile exercise by the accused. In the illustration to Section 511, the code aptly explains the principle: Thus A, intending to pick he pocket of B thrusts his hand into the pocket of B but finds nothing, A is guilty of an attempt to commit theft. If the attempt is successful, the crime is committed. But even if the attempt is unsuccessful, the person committing the attempt is liable to be punished. The difference between preparation and attempt is very thin and it is difficult to conclude where preparation ends and attempt begins. The question requires to be decided on the facts and circumstances of each case. If there is no specific provision for the punishment of attempt, Section 511 will apply and the accused will be punished accordingly.
The last stage to the commission of the crime is the accomplishment of the crime or the actual act of the crime. Where the person succeeds in his attempt to commit the crkme he is obviously responsible for such an act and he will be punished accordingly. Thus if A intending to ill B (Intention), purchases a pistol to do the same (preparation), fires at (Attempt) and therefore kills B (B); A will be held liable for committing the offence of murder and will accordingly be punished.