*Membrane Computing* is an emergent branch of
*Natural Computing* introduced
by G. Paun. This new model of computation starts from the
assumption that the processes taking place in the
compartmental structure of a living cell can be
interpreted as computations. The devices of this model
are called **P systems**. Roughly speaking, a P system consists of a
cell-like membrane structure, in the compartments of which one
places multisets of objects which evolve according to given rules.

Most variants of membrane systems have been proved to be
computationally complete, that is equivalent in power to Turing
machines, and computationally efficient, that is able to solve

computationally hard problems in polynomial time.
Although most research in P systems concentrates on
computational powers, lately they have been used to model
biological phenomena.

As P systems are inspired from the
structure and functioning of the living cell,
it is natural to consider them as modelling tools for biological
systems, within the framework of **Systems
Biology**, being an
alternative and complementary to more classical approaches like
*Ordinary Differential Equations*
(ODEs) and to some recent approaches like *Petri
nets* and *π-calculus*.

P system models take into consideration the discrete character of the quantity of components and the inherently randomness in biological phenomena. Besides, the key feature of P systems is the so called membrane structure which represents the heterogeneity of the structural organisation of the cells, and where one can take into account the role played by membranes in the functioning of the system.

The site has been produced by John Auld, Francisco Romero-Campero, Marian Gheorghe.