Being adapted to an environment means an organism has really good features to increase its chances of survival. Therefore, these organisms will be more likely to successfully reproduce and pass on these adaptations on to their offspring. Over time the organism becomes very well adapted to the environment. This can include:
Behavioural adaptations - they way an organism acts to survive
Physiological adaptations - processes such as metabolism that aid survival
Anatomical adaptations - structural usually visible features that help them survive
These adaptations are the way an organism will act to help itself survive. This can involve aspects to help them hunt, hide, sleep, deal with the environment etc. Behavioural adaptations are passed down and recognised by other members of the species, again leading to the adaptation becoming common. A few examples:
Possums play dead to make themselves less appealing to feed on. The most convincing possums survive.
Scorpions dance to attract mates, the best dance will attract the best females, so good couples will reproduce and produce very well adapted offspring. Mating patterns are seen a lot in nature, birds etc. it is all about attracting the best mate, to pass on the genes. The mate with the best dance will often have very desirable characteristics to pass on to offspring,
Hedgehogs roll up to protect themselves from predators, revealing their spiky 'fur' that is unattractive and painful to predators.
These involve processes inside an organism that aid their survive a little less obviously. It is down to molecular science. A few examples are the best way to describe this:
Hibernation - many animals hibernate in winter months when food is scarce, this may seem like a behavioural adaptation but the survival is really down to metabolism. During hibernation the organisms metabolism lowers which in turn conserves energy, since the animal does not need the energy this is perfectly efficient. The energy is directed to maintaining the basic necessities for survival. The animal does not need to look for food so much. So they are more likely to survive if they have a good metabolism! (a good metabolism would be getting the maximum energy available from the food, with little resulting as waste)
Bacteria produce antibiotics which kill other species in an area. This results in less competition so they are more likely to survive,
Snakes can produce venom, the most powerful venom will be more likely to kill prey or even an attacker. Again this helps survival through hunting methods and protection