The literature on JIT and Lean contains several seminal books, amongst them by Womack and Jones, Schonberger, Hall, Goldratt, and Imai. These built on the "greats": Deming, Juran, and Ohno. To distil them is a daunting task, but certainly there are common themes. These 18 seem to be at the core:

• Customer. The external customer is the starting and ending point. Seek to maximise value to the customer. Optimise around the customer, not around internal operations. Understand the customer's true demand, what he would really like, not what can be supplied.
• Simplicity. Lean is not simple, but simplicity pervades. Simplicity in operation, in system, in technology, in control is the goal. Simplicity applies to product through part count reduction and commonality. Simplicity applies suppliers through working closely with a few trusted partners. Simplicity applies in the plant, by creating focused factories-within-a -factory. Beware complex computer systems, complex and large automation, complex product lines, complex rewards. Select the smallest, most simple machine possible consistent with quality requirements.
• Waste. Waste is endemic. Learn to recognise it, and seek to reduce it, always. Everyone from chairman to cleaner should wear "muda spectacles" at all times.
• Process. Organise and think by the process view. Think horizontal, not vertical. Concentrate on the way the product moves, not on the way the machines or people or services move. Map to understand the process.
• Visibility. Seek to make all operations as visible and transparent as possible. Control by sight. Adopt the visual factory.
• Regularity. Regularity makes for "no surprises" operations. We run our lives on regularity (sleep, breakfast, etc); we should run our plants on this basis too. Seek "repeater" products and run them in the same time slots - this cuts inventory, improves quality, and allows simplicity of control. "Time pacing" in new product introduction shortens the development cycle and makes innovation the norm.
• Synchronisation. Seek "keep it moving" manufacture. Seek flow. Synchronise operations so that the streams meet just in time. Synchronisation should be the aim both within company and along supply chains.
• Small Batches. Aim for one-piece flow. Break with batch and queue thinking. If one-piece is not possible, seek to minimise batch sizes. This applies not only to physical products but to designs and information. Small batches for flexibility, quality, time, and cost. In information flow, enter the data immediately and once only into digital form.
• Pull. Seek for operations to work at the customer's rate of demand. Avoid overproduction. Have pull-based demand chains, not push-based supply chains. Pull should take place at the customer's rate of demand. In demand chains this should be the final customer, not distorted by intermediate "bullwhip" effect.
• Postponement. Delay activities and committing to product variety as late as possible so as to retain flexibility and to reduce waste and risk. This characteristic is closely associated with the concept of avoiding overproduction, but includes plant and equipment, information, and inventory. Note that this is not the same as simply starting work at the last possible moment, but is about retaining flexibility at the right levels.
• Prevention. Seek to prevent problems, rather than to inspect and fix. Shift the emphasis from failure and appraisal to prevention. Inspecting the process, not the product, is prevention.
• Time. Seek to reduce overall time to make, to deliver, and to introduce new products. Use simultaneous, parallel, and overlapping operations in operations, design, and support services. Seek never to delay a value-adding step by a non value-adding step. Time is the best single overall measure.
• Improvement. Improvement, and continuous improvement in particular, is everyone's concern. Make improvement both "enforced" and passive, both incremental and breakthrough. Improvement goes beyond waste reduction to include innovation.
• Partnership. Seek co-operative working both internally between functions, and externally with suppliers. Seek to use teams, not individuals, internally and externally. Employees are partners too. Seek to build trust.
• Value Networks. The greatest opportunities for cost, quality, delivery and flexibility lie with co-operating networks. Supply chains compete, not companies. But each member also needs to add value. Expand the concept of the one dimensional supply chain to a two-dimensional value network.
• Gemba. Go the workplace and seek the facts. Manage by walking around. Implementation takes place on the floor, not in the office. Encourage the spirit of Gemba throughout.
• Variation. Variation is found in every process. Seek to reduce it. Measure it, know the limits, and learn to distinguish between natural variation and special events. Manage it. Build in appropriate flexibility. Shockproof the system.
• Participation. Give operators the first opportunity to solve problems. All employees should share responsibility for success and for failure. True participation implies full information sharing.