Percentiles are also used in the context of talking about the quartiles in a distribution. Let's look at a normal distribution to understand this better.

Here's an example illustrating Percentile in normal distribution:

Looking at the normal distribution in the preceding image, we can talk about quartiles. Quartile 1 (Q1) and quartile 3 (Q3) in the middle are just the points that contain together 50% of the data, so 25% are on left side of the median and 25% are on the right side of the median.

The median in this example happens to be near the mean. For example, the interquartile range (IQR), when we talk about a distribution, is the area in the middle of the distribution that contains 50% of the values.

The topmost part of the image is an example of what we call a box-and-whisker diagram. Don't concern yourself yet about the stuff out on the edges of the box. That gets a little bit confusing, and we'll cover that later. Even though they are called quartile 1 (Q1) and quartile 3 (Q1), they don't really represent 25% of the data, but don't get hung up on that yet. Focus on the point that the quartiles in the middle represent 25% of the data distribution.