Significant figures are the digits of a number that are meaningful in terms of accuracy or precision.

Every scientific measurement involves some degree of uncertainty. In order to report a measurement correctly and precisely, the scientists use the concept of significant figures. The significant figures are defined as the total number of certain digits plus one doubtful digit in a number expressing a measurement. For illustration of this term, let us suppose that we want to measure the mass of an object with the help of an analytical balance. Let us further suppose that the measured mass of the object comes out to be 30.1296 g. Now, the analytical balance can record the mass of the object to a sensitivity of 0.0001 g. Thus, all the figures reported are significant. The reported value (30.1296 g) has six significant. figures. Though the last figure has some uncertainty but even then it is significant. Because this implies that the true mass of the object lies closer to 30.1296 g than to 30.1295 g or 30.1297 g. This is the most precise value of the mass measured with analytical balance.