Worldlang (eo: mondfonta planlingvo ) is a class of artificial languages using languages of the whole world as its source.
The number of source languages may vary from six at Lojban (Chinese, English, Hindi, Spanish, Russian, Arabic) to any possible number.
The oldest project maybe was Sona (1935). Old projects of the XX century (Sona, Loglan , Lojban) severely distorted source words/roots, or used sophisticated methods for mixing them. New worldlangs of the XXI sentury have more naturalistic approach for using lexics. They are such languages as:
Lingwa de Planeta (Lidepla, LdP)
Pandunia
Tceqli (Ceqli)
Noxilo
Seytil
Globasa
and others.
Difficulties of classification
Sambahsa -mundialect uses Indo-European languages as its source. It looks like close to be a worldlang, but having lack of using Chinese, Arabic or another non-Indo-European languages, maybe Sambahsa is not a worldlang in full sence.
Toki Pona apparently is a worldlang, but due to its originality it ruther is regarded as a standalone project than being classified.
Old projects, such as Sona, Lojban, much differ from the new projects of the XXI сentury, so when we say about worldlangs we mean the projects of the new wave at first.
Advantages
Worldlangs are regarded as more neutral, more justful then eurocentric projects.
Disadvantages
The languages of the world differ very much, so the creators have too much liberty arbitrarily selecting lexics according to their own criteria. As a result, their artificial languages also much differ.
In the majority the students of auxilary languages are europeans, such languages as Esperanto or Interlingua are easier to learn for them.