How do plants avoid being eaten?

Hint: The ways plants avoid being eaten are called plant defence mechanisms. They have numerous ways in order to protect themselves from predators. Since herbivores are the main consumers of plants, plants have special defence mechanisms against them.

Complete answer:
There are numerous ways of plant defence mechanism which are listed as below-

Mechanical defence mechanism- Plants naturally have waxy cuticles and hard barks which offer resistance to many attackers. This is also called the first line of defence as these are generally present on the surface which is initially approached by the herbivores. Some plants have modified their branches into thorns and some have modified their leaves into spines. For example, cactus has spines (modified leaves) to protect against predators.

Chemical defence mechanism- Secondary metabolites are compounds which are not directly involved in plant growth, development or photosynthesis but are involved in plant defence mechanisms. Some metabolites such as alkaloids (e.g. caffeine) or opioids and glycol cyanide have deadly effects on animals. The chemicals are generally volatile organic compounds.

Note: In addition to the chemical and mechanical defences which are used to keep attackers at a distance, there are other mechanisms too to avoid being eaten away by intruders. For e.g. a very well-known plant, touch-me-not when touched droops down giving it an impression of dead and inactive plant which is not approached by animals further.
Nature has its own way of dealing with the atrocities of nature whether plants or animals or any other species.