IT architectures are enjoying a renaissance. CIOs are updating yesterday's architectures, or working on creating new ones. The reason? IT architectures promise benefits that are more sought after than ever. But they are not always easy to explain to your non-IT colleagues.

In its simplest form, an IT architecture is a set of technical guidelines and standards to guide the enterprise in satisfying business needs. They comprise sets of policies, rules, guidelines and standards that guide the technical choices organisations make. These choices help implement business strategies with an eye to the futureAt their most granular level they identify preferred technologies and vendors, templates, tools and methods, and standards for, say, applications and interfaces.

IT architectures are like planning regulations. Think city planning regulations when you think IT architecture. These are guidelines that establish what can and can't be done; they act as brakes on the size, shape and position of such things as roads, walkways, buildings, lighting and water systems.

An IT architecture has a number of "layers" and the point is to get all the layers working together smoothly. The first layer is business goals, strategy and maxims that shape the type of architecture you need. The second is core business processes that aid the implementation of strategy, and, finally the layer that includes data, applications and infrastructure.

Important benefits of an IT architecture are lower IT costs through simplification and the ability to interconnect enterprises and people. An increasingly inter-connected economy demands improved interoperability so that enterprises can link processes and services, supply chains and customers across businesses and across geographies.

Implementing architectures demands discipline and strong business drivers. IT architectures are easy to get wrong. Benefits are difficult to isolate and costs have a habit of spiralling. IT architectures sacrifice local autonomy in favour of overall synergy, so they frequently give rise to political tension.

Most leading enterprises are now shifting to taking an architectural approach to the development of systems. It is part of increasing maturity in how enterprises integrate technology into their business processes. But it is not simple. Defining and gaining compliance for IT architectures takes discipline and a fine balance between business needs and goals, then what makes sense technically. The exemplars we see in Gartner's Executive Programs CIO community have business-driven architectures, but also good processes for handling exceptions.

Identifying different architectural strategies. IT architecture can be grouped into four architectural strategies according to their features and benefits. Bruce Rogow of e-business integrator Differentis refers to these as architectures that consolidate, connect, innovate or re-platform.

Consolidate architectures emphasise IT cost reduction and systems simplification. They use a range of building blocks (business process, reusable modules or software components). The popularity of integrating servers into data centres in the 1990s brought consolidate architectures to the fore.

Connect architectures, which are currently popular, emphasise interconnecting across an enterprise and even between enterprises. They identify standard interfaces and middleware - the software glue for holding incompatible systems together.