Dendrobium is a massive genus containing more than (conservatively) 900 species. These range from cool-growing miniatures to huge specimen plants growing in hot conditions year round. The most commonly found types of Dendrobium are the phalaenopsis type (commonly known as den-phals, and named for the species most used in their breeding, which used to be known as Dendrobium phalaenopsis, but which is now known as Dendrobium bigibbum), and the nobile type (named for the species most used in their breeding, which is known as Dendrobium nobile).
Orchids of all types have also often been sought by collectors of both species and hybrids. Many hundreds of societies and clubs worldwide have been established. These can be small, local clubs, or larger, national organisations such as the American Orchid Society. Both serve to encourage cultivation and collection of orchids, but some go further by concentrating on conservation or research.
Most orchids are not heavy feeders. Many orchids bloom year after year with no fertilizer at all. During active growth, when new leaves are being produced, you may fertilize every other time you water at half the strength recommended on the fertilizer package. However, it's important to deliver water without fertilizer at least once a month to flush excess fertilizer salts from the bark mix and avoid fertilizer burn to the roots.