When drawing an inference (from a sample statistic, about a population parameter), there can be two types of errors: Type I and Type II.
Type I error, also known as error of the first kind, occurs when the null hypothesis is true, but is rejected.
Type II error, also known as the error of the second kind, occurs when the null hypothesis is false, but is accepted as true.
The following video explains these errors with examples.
This video is developed by David from Bionic Turtle.