Organic, ecological or (in many other languages) biological farming is a kind of agriculture that tries to respect nature, environment and animals. There are several associations that have their standards and control the farmers. Of course, any agriculture is a work with organic, ecological and biological processes, so it has to be admitted that these expressiones here have a special meaning.
The certificate has been created to offer a certain transparency to the customers. Therefore in mer selfsufficiency production, the certificate usually is of no use.
In organic farming (or agriculture) crop rotation and natural fertilizers (like manure, compost) play an important role. Chemical fertilizers, many (but not all) pesticides and all products of genetically modified organisms are forbidden.
Of course, not in every case has been found the ideal solution yet, for example how to control certain pests, therefore further research is being made.
It is not about preaching a simple dualism that products from organic farming are always better than other products. For example, palm oil, even though it has a certificate as organic or sustainable, contributes to the destruction of the Malay and Indonesian virgin forest and for this reason should be avoided.
No hay que predicar un simple dualismo que los productos de la agricultura ecológica sean siempre mejores que los otros. Por ejemplo, el aceite de palma, aunque tenga certificado de ser ecológico o sostenible, contribuye a la destrucción de la selva malaya e indonesia y por eso es de evitar.
The standards only refer to the production, not for example to transport. So you can buy apples from organic growth that have been transported with a lot of energy consumption from Australia or Argentina to Europe, what from an ecological point of view is counterproductive. Here it is the consumers' task to stay critical and focus on local produce of the season.
On the other hand, products from transhumant livestock keeping cannot usually receive an organic certificate because the herdsperson does not have control over the management of the pastures. Nevertheless, on many cases this form of eocnomy creates worthy ecosystems. So it is nothing to be disdained if a shop specialized in ecological products sells their products, provided there is transparency for the consumers.
Something which can actually be considered counterproductive to organic farming, is that more and more natural food shops sell products based on soya (mostly genetically modified unless stated otherwise on the package) and palm oil to satisfy the needs of the vegan fashion, needs created by economical interests.
French: agriculture biologique
Pests in the garden in the ABC of Medicinal Plants (in Spanish)