Think of heading styles like an outline. In an outline, sub-sections are nested within the "superior" section. Headings follow the same structure, as shown below.

[NOTE: The heading rank is indicated in parentheses for description only. Do not include the heading rank on your content pages.]

EXAMPLE 1-

Main Section 1 (Heading 2)

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Main Section 2 (Heading 2)

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Sub-Section A within Section #2 (Heading 3)

Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

Sub-Section B within Section #2 (Heading 3)

Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

Sub-Section #1 within Sub-Section B (Heading 4)

Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

Sub-Section #2 within Sub-Section B (Heading 4)

Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

Sub-Section C within Section #2 (Heading 3)

Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

Main Section 3 (Heading 2)

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

EXAMPLE 2-

Vertebrates (H2)

Vertebrates, animals with backbones, include the jawless fish and the jawed vertebrates, which include the cartilaginous fish (sharks, rays, and ratfish) and the bony fish. Vertebrates make up less than five percent of all described animal species.

Mammals (H3)

Mammals are warm-blooded, hairy bodied and possess a neocortex region of the brain. Females of all mammal species nurse their young with milk, secreted from the mammary glands.

Monotreme (H4)

Examples of monotreme mammals (mammals that lay eggs) are the platypus and the echidna, sometimes known as spiny anteaters.

Marsupial (H4)

All extant marsupials are endemic to Australasia and the Americas. A distinctive characteristic common to these species is that most of the young are carried in a pouch. Well-known marsupials include kangaroos, wallabies, koalas, possums, opossums, wombats, and Tasmanian devils.

Placental (H4)

A placental mammal is any member of the mammalian group characterized by the presence of a placenta, which facilitates exchange of nutrients and wastes between the blood of the mother and that of the fetus. The placentals include all living mammals except marsupials and monotremes.

Fish (H3)

Fish are the gill-bearing aquatic craniate animals that lack limbs with digits. Most fish are ectothermic ("cold-blooded"), allowing their body temperatures to vary as ambient temperatures change, though some of the large active swimmers like white shark and tuna can hold a higher core temperature.

Birds (H3)

Birds are a group of endothermic vertebrates, characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton. Birds live worldwide and range in size from the 5 cm (2 in) bee hummingbird to the 2.75 m (9 ft) ostrich.

Birds of Prey (H4)

Birds of prey include eagles, hawks, kites, secretary birds, ospreys, falcons and old world vultures, about 300 species in all. Also known as raptors (but not all that closely related to the raptor dinosaurs of the Mesozoic Era), birds of prey are formidable predators, armed with powerful talons, hooked bills, acute eyesight, and broad wings well-suited for soaring and diving. Raptors hunt by day, feeding on fish, small mammals, reptiles, other birds, and abandoned carrion.

Perching Birds (H4)

Perching birds, also known as passerines, are the most diverse bird group, consisting of over 5,000 species of tits, sparrows, finches, wrens, dippers, thrushes, starlings, warblers, crows, jays, wagtails, swallows, larks, martins, warblers and many others. True to their name, perching birds have a unique foot structure that allows them to tightly grip thin branches, twigs, slender reeds and flimsy grass stems; some species can even hold fast to vertical surfaces, such as rock faces and tree trunks.

Gamebirds (H4)

Some of the most familiar birds on earth, at least to people who like to eat, gamebirds include chickens, pheasants, quails, turkeys, grouse, curassows, guans, chachalacas, guineafowl and megapodes, about 250 species in all. Many of the world's less familiar gamebirds are subject to intense hunting pressure and are today on the brink of extinction.

Ostriches (H4)

The sole extant member of its order of birds, the ostrich (Struthio camelus) is a true record-breaker. Not only is it the tallest and heaviest living bird, but it can sprint at speeds of up to 45 miles per hour, as well as jog for extended distances at a sustained pace of 30 mph. Ostriches have the largest eyes of any living terrestrial vertebrate, and their three-pound eggs are the largest produced by any living bird.

Invertebrates (H2)

Invertebrates are animals that neither possess nor develop a vertebral column (commonly known as a backbone or spine), derived from the notochord. The majority of animal species are invertebrates; one estimate puts the figure at 97%.

Spiders (H3)

Spiders are air-breathing arthropods that have eight legs and chelicerae with fangs that inject venom. They are the largest order of arachnids and rank seventh in total species diversity among all other orders of organisms.^[2] Spiders are found worldwide on every continent except for Antarctica, and have become established in nearly every habitat with the exceptions of air and sea colonization.

Insects (H3)

Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of jointed legs, compound eyes and one pair of antennae. They are the most diverse group of animals on the planet, including more than a million described species and representing more than half of all known living organisms.

Ant (H4)

Ants are eusocial insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the Cretaceous period, about 99 million years ago, and diversified after the rise of flowering plants.

Bee (H4)

Bees are flying insects closely related to wasps and ants, known for their role in pollination and, in the case of the best-known bee species, the European honey bee, for producing honey and beeswax. There are nearly 20,000 known species of bees in seven recognized biological families.

Ladybug (H4)

Ladybugs are members of the coccinellidae family, a widespread family of small beetles ranging from 0.8 to 18 mm (0.03 to 0.71 inches). They are commonly yellow, orange, or red with small black spots on their wing covers, with black legs, heads and antennae. However such colour patterns vary greatly.

Octopuses (H3)

The octopus is a soft-bodied, eight-armed mollusc of the order Octopoda. Around 300 species are recognised and the order is grouped within the class Cephalopoda with squids, cuttlefish and nautiloids. Like other cephalopods, the octopus is bilaterally symmetric with two eyes and a beak, with its mouth at the centre point of the arms (which are sometimes mistakenly called "tentacles").

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