The stone slabs on top of a grave are called Gravestones or headstones. They are defined as monuments, inscribed with names, date of births, date of deaths and few other words quoted or dedicated to the person lying in the grave which can be same or different. It can be a quite fancy design to symbolize a family sign or frame and it can be simple with a common shape, it all depends on the wishes of the deceased and family. There is no other purpose than to symbolize and mark the place where the certain person lays for the future generation if they need to trace family history. It makes it easier to locate the grave when needed.
These all headstones or gravestones may give the same type of information but there are different types of these stones which can be chosen according to the likes and family rules.
The flat gravestone is the type of gravestones which is set flat on the ground, maybe with a flat base. These are also called flush base or lawn level marker. These are quite simple ones and cost lesser than others. These gravestones are only available in granite and bronze and can occasionally be only made up of concrete if needed. If the chosen material is granite, it can be further chosen with colour. The most common type of headstone is upright ones. Upright headstones are the headstones standing perpendicular to the grave in a form of tablet with have all the engraving on it. To keep it straight it has vertical support, making the two-piece gravestone and of course, costing more than a flat one. A slant marker is the type of gravestone which has a slanted angle of, more or less, 45 degrees with a tapered top. The base is quite wide which has all the information on it. This is one of the most used types of memorial plaques for the family head or other important people. Its slant is on top of a granite or cement base. Bevel marker is one of the newer types of a gravestone. It is like a slant marker but has a steeper angle and is in the back and front are both raised a lot higher than usual markers. It gives a look of a raised slanted slab making it higher than others.
There are other types which can be considered quite different. Some can be gothic, giving a darker look while some can have another peculiar style tablet, based on the wishes of the deceased. It is not common but can be seen sometimes.