Dispersion is the spreading of a population or organism away from its parents and happens when organisms are looking for additional resources or as an adaptation to environmental changes. Dispersion is influenced by various environmental factors such as temperature or terrain. Animals disperse by moving, while plants have seed dispersal.
Dispersion basically means to spread, so in Biology they'll talk about the dispersion of a population or dispersion of a particular organism away from either it's parental population or from it's original parent. Now why would you want to spread out? Well obviously that gives you access to new resources, so when a plant spreads it's seed it's trying to get it's seeds into other areas to get more soil, water and other things that it needs in order for it's offspring to grow as opposed to sitting right next to the plant where it may wind up having to compete with it's parent, and this also allows you to adopt to environmental changes for example as the global climate change may occur you may notice that the temperature ranges where mosquitoes can fly and thus carrying malaria with them starts spreading, so people may disperse and move to other areas to get away from these areas of high malarial outbreaks.
Now as I just mentioned this can be influenced by lots of various different kinds of environmental factors whether it's things like temperature and rainfall or terrain, even other organisms can influence how one disperses. Now the standard mechanisms that you will see with animals is we move, whether we fly or just walk but we can move away from our parents or from our parent populations by simply moving. Now there are some animals that don't move very much, they are called "non-mortal" well for example that might be seeing enemies or sponges and other "sisal" organisms, well they may have specialized structures that allow them to spread when that kind of event occurs or they may spread during reproduction for example tapeworms they typically don't sit there and chase after their prey instead they just make lots of eggs and when somebody has a tapeworm and go to the bathroom those egg cases wind up spreading out and then if anybody winds up accidentally ingesting them because of poor sewage, treatment or whatever, that animal has now dispersed it's eggs into a new host to get access to those new resources.
Now plants obviously rarely move, so how do they disperse themselves, how do they disperse their populations? They typically have specialized forms of seed dispersal, now in flowering plants they often will use animals as ways of spreading their seeds that's why they produce fruit. So an animal come along eat the fruit as a bribe and then they wonder away from mummy or daddy plant and take that seed elsewhere so that 24-48 hours later outcomes the seed elsewhere, so it's not competing with it's parental plant. Many plants use seeds that can flow in the air whether it's the helicopter seeds that you sometimes see coming out of a pine trees or the dandelions that you make a wish your dad sitting there wishing that you wouldn't blow dandelion seeds all over his lawn. These are all ways that plants take advantage of whether it's us or other environmental cues, even sometimes gravity ferns may just release their spores and hope that they bounce a lot when they hit the ground there's even some amongst some of the plants, they have swimming supermen eggs and so perhaps they might be able to send their little guys out a little bit further. So there you go that's how you can do dispersion.