37 °C is a value that one encounters probably more often than any other temperature reading. If you are used to the Celsius scale, you recognize it immediately. Indeed, a normal body temperature of a healthy person is in the vicinity of 37 degrees Celsius, which makes this value so special and important. For the Fahrenheit folks, you may know it as 98.6 °F (as you can easily verify using our online converter).
It is important to realize however that the 37 Celsius (or 98.6 Fahrenheit) value is essentially an averaged benchmark. What is "normal" depends on various factors, both objective and subjective. At least some of those factors should be taken into account when reaching conclusions about whether one's body temperature is normal.
Some objective factors affecting our body temperature include the time of day (with the lowest temperature in the morning and the highest typically around mid-afternoon), recent exercise (you get hot after a long run for instance), a recent meal, warm and/or alcoholic drinks, etc. All of these aspects can easily make one's temperature fluctuate within one or two degrees.
There are also subjective factors, such as the way body temperature is being measured, the instrument (thermometer) type being used, etc. For example, oral and under the arm readings commonly differ (oral being higher), and fast digital thermometer readings may not always be as accurate as longer liquid column thermometer measurements.
To summarize, the message we would like you to keep in mind is that the "normal body temperature" is more of a range rather than a well-defined number, and it should be relied on with reasonable flexibility. We wish you to stay healthy, and in cases when you do need to take a measurement and the only thermometer you have is not marked in the units you like, here is a chart that should help.