All negligence matters fall within the broad area of law known as tort law. Negligence matters are among the most common torts that give rise to litigation claims (lawsuits) and often involve injury to persons or damage to property caused by the carelessness of others such as the failure to properly keep walkways safe resulting in a 'slip and fall'. Negligence was recently defined in Seyom v. TTC, 2018 ONSC 6848 as:
 Generally speaking, negligence is the doing of something which a reasonably prudent person would not do, or the failure to do something which a reasonably prudent person would do, under circumstances similar to that found in a case. Negligence is relative to the circumstances. Negligent conduct gives rise, through an act or omission, to an unreasonable risk of harm.
A case in negligence may be founded when:
- There is a duty of care owed;
- There is a standard of care owed that has been unreasonably breached;
- There is harm as result of the breach that was reasonably foreseeable; and
- There are no public policy reasons to negate liability.
Duty of Care
"The duty of care in negligence law is based upon a relationship of proximity between parties which requires one person to take reasonable care for the protection of the other."1
The duty of care owed to those within a relationship of proximity is known as the 'neighbour principle' per the precedent in Donoghue v. Stevenson,  A.C. 562 where it was said by Lord Atkin at page 580:
You must take reasonable care to avoid acts or omissions which you can reasonably foresee would be likely to injure your neighbour. Who, then, in law is my neighbour? The answer seems to be - persons who are so closely and directly affected by my act that I ought reasonably to have them in contemplation as being so affected when I am directing my mind to the acts or omissions which are called into question.
Standard of Care
The standard of care in negligence law is based upon the failure to do what a reasonable person would do, or failure to refrain from doing what a reasonable person would refrain from doing, when faced with the same circumstances; Seyom, supra at paragraph 6. It is important to keep in mind that a 'reasonable person' is merely a fictitious person. The test is one of whether the risks of harm were reasonably foreseeable such that proper care should be taken at the time, without considering afterward, with 20/20 hindsight, whether the risks of harm were a possibility - as by using such a hindsight test, whenever there has been an occurrence of harm stemming from a risk, the possibility of the risk actually occurring would be shown as absolute. Determining whether there was a breach of the standard of care is a considerably different question than asking whether an occurrence of a potential risk took place.
1 Lewis Klar, Tort Law, 3rd ed. (Toronto: Carswell, 2003) at 153 [Klar]