Glue
Glue sticks voxels and objects together. They are represented as studs upon editing an object. At the core, two voxels stick together if and only if their glue are directly touching each other. This means you may have multiple separate objects in a single edited block.
Blocks placed next to each other automatically group into a single larger object. This is great for static things, such as a level, which will create a shading known as ambient occlusion and draw efficiently to keep the game running smoothly.
For moving things, you probably do not want them to glue to nearby blocks. For example, if you use script to move a character, and it has glued to the level, the entire level will move too! So you want to remove the glue from the character block's sides.
Removing glue dots requires editing the block. In case you have complex moving shapes, and do not want to make a lot of custom blocks with various glue sides, another method is to build the whole moving object off the sides, so its blocks don't directly touch e.g. the level blocks. Then use Play Sensor to move it into place on Play, it will happen before the first frame is drawn, so completely unnoticeable to the player.