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It is the normalised Gaussian distribution. To speak of a 'standard z' distribution is somewhat redundant because a z-score is already standardised. A z-score follows a normal or Gaussian distribution with a mean of zero and a standard deviation of one. It's these specific parameters (this mean and standard deviation) that are considered 'standard'. Speaking of a z-score implies a standard normal distribution. This is important because the shape of the normal distribution remains the same no matter what the mean or standard deviation are. As a consequence, tables of probabilities and other kinds of data can be calculated for the standard normal and then used for other variations of the distribution.
The Gaussian distribution is the single most important distribution.
Not all univariate data will be normally distributed. Graphing the data will help you determine if you got the kind of distribution you were expecting, and if not, what kinds of tests will be appropriate for what you got. A strange distribution when you had reason to expect, say, a normal distribution would help you uncover possible problems with data collection.
Events occurring independently, singly and at a constant rate (in time or space).
In Excel you can use all sorts of things. You can do it with formulas to see when things are exactly equal, or do things like create charts to compare data.