First of all, let us understand edge dislocation. In edge dislocation, there will be defect in edges of the crystal. Suppose, the crystal is in the rectangular form just like this. Now let us consider a scenario in which this lower breath is constant. Now this upper breath keeps on expanding and expanding. Then what happens? There is the creation of defect. That is what happens in case of edge dislocation. Are you getting confused? Let us understand this by a diagram which will help us understand this very properly. Now look at here, the ideal crystal or the perfect crystal is in this type of shape. And that means the atoms are arranged in a proper way. Suppose this is the perfect crystal. This is the perfect crystal. This is the crystal structure and the atoms are in there. Crystal lattice. That is lattice side. They are in there. This side lattice side is like home of atoms in a crystal. This is the ideal crystal. Now let us consider another plane, half plane. How many atoms are there? 1, 2, 3, 4 in this line. That is in y axis. How many atoms are there? 1, 2, 3 and 4. 4 atoms are there. And this is the half part of this total line right, total crystal. Then let us consider a half plane in which there are two atoms. That means there will be a term, sorry, the plane will be like this. We insert a plane over here. We insert a plane over here. Now by inserting the plane what happens? Each atoms will get repelled and these atoms will change its position. This atom will come here. This atom will come here. Similarly this atom again comes here and this atom comes where here. Now what happens? This is the new structure that we get. This is actually the new crystal that we get. Now these two are the edges of the crystal. Now look at here this lower edge or the lower breath is constant. The length of lower breath is constant but the length of upper breath is expanding right. It is increasing. So this is not a perfect crystal anymore. Now this defect is along the edges of the crystal. These are the edges of the crystal. So these defects are called edge dislocation. Now if you need to write it, how do we write it? Look at here in edge dislocation, in edge dislocation and extra plane and extra plane is inserted, in the crystal extra half plane. Extra half plane is inserted in the crystal that creates the defect along the line and edge called what? Edge dislocation, edge, edge, edge, location. So you just saw over here. Initially the crystal was in perfect shape but when we insert the half plane then the shape of the crystal is distorted. So this is the creation of defect that is called edge dislocation defect. We generally find this type of form in which we get half plane in that. So this is what we call edge dislocation. Now if this moves this is called slip. You can see over there this is reverse T right? This is reverse T. So if we get reverse T effect this is called positive, positive edge dislocation, edge dislocation and if it is like this non-reversed T if the plane was inserted from lower side then this would be called negative edge dislocation. So this is what we called edge, this is what edge dislocation actually is.