A margin trowel is a trowel used to spread grout or other material in tight spaces. A margin trowel is more narrow than a regular trowel for this purpose. A margin trowel comes in a variety of edges including a v-shaped back with a flat edge or they can come with teeth.
When working in small spaces like corners, it can be very hard to use a regular size trowel. A margin trowel will save you a lot of trouble and stress.
To learn more about the different types of trowels, watch the video below: