Supply Chain, WMS and ERP: The Terms You Need to Know

Supply chain questions are mostly vocabulary with a practical meaning attached: an abbreviation, a rule of thumb or a process, and the right answer is the definition that matches how the term is used on a warehouse floor or in a planning meeting. This guide groups the vocabulary by what each term does, which is far easier to remember than an alphabetical list.

The systems: how WMS, ERP and TMS fit together

• ERP (Enterprise Resource Planning) — the company-wide backbone covering finance, purchasing, sales, manufacturing and inventory in one database. SAP and Oracle are the best-known ERP vendors.
• WMS (Warehouse Management System) — software that runs the inside of a warehouse: receiving, put-away, storage locations, picking, packing and shipping. It tells staff where to put and what to pick.
• TMS (Transportation Management System) — plans and tracks the movement of goods: carrier selection, routes, freight cost and delivery status.
• OMS (Order Management System) — captures and orchestrates customer orders across channels.

A handy way to keep them apart: ERP knows what the business owns and owes; WMS knows where every item physically sits; TMS knows how it moves between places.

Identifying and tracking goods

• SKU (Stock-Keeping Unit) — a unique identifier for each distinct inventory item (including its size, colour or variant).
• Barcode, QR code and RFID — ways of capturing identity automatically; RFID reads tags by radio without line of sight. GS1 is the global standards body behind barcodes.
• Traceability — the ability to follow a product's history, location or use through recorded information.
• Unit load — a quantity of items arranged or restrained together (typically on a pallet) so they can be handled as one.

Inventory rules: which stock leaves first

Related ideas: ABC analysis ranks items by value or movement (A items are few but account for most value; C items are many but minor), and cycle counting checks small portions of inventory regularly instead of a once-a-year full stocktake.

Receiving and storing

• ASN (Advance Shipping Notice) — an electronic message from a supplier that tells the warehouse what is coming, so it can plan receiving. It is typically sent using EDI (Electronic Data Interchange), the standardised exchange of business documents between computers.
• Put-away — moving received goods from the dock to their storage location.
• Slotting — assigning products to storage locations to improve picking and replenishment efficiency (fast movers close to the packing area).
• Cross-docking — moving goods directly from inbound to outbound with little or no storage in between.

Picking: how orders are fulfilled

• Discrete picking — one order at a time. Batch picking — several orders picked together. Zone picking — each picker covers one area. Wave picking — orders released in scheduled groups.
• Pick-to-light — a system that uses lights or displays to direct the picker to the correct location.
• Voice picking — instructions are given through a headset.
• AGV and AMR — automated guided vehicles follow fixed paths; autonomous mobile robots navigate more freely.

Planning formulas and measures

• Lead time — the time between placing an order and receiving it.
• Safety stock — a buffer held against uncertain demand or supply.
• Reorder point (ROP) — the stock level that triggers a new order: roughly demand during lead time plus safety stock.
• EOQ (Economic Order Quantity) — the order size that minimises combined ordering and holding costs; the classic formula is the square root of (2 × annual demand × cost per order ÷ holding cost per unit).
• MOQ (Minimum Order Quantity) — the smallest quantity a supplier will accept.
• MRP (Material Requirements Planning) — calculates what materials are needed, and when, from the production schedule and the BOM (Bill of Materials), the list of components in a product.
• DRP (Distribution Requirements Planning) — the same logic applied to replenishing distribution centres.
• JIT (Just-in-Time) — receiving goods only as they are needed, keeping inventory low.
• S&OP (Sales and Operations Planning) — the regular process that aligns demand forecasts with supply plans.
• Demand sensing — using near-real-time signals to improve short-term forecasts.
• ATP (Available-to-Promise) — the quantity that can be promised to a customer without disturbing existing commitments.
• OTIF (On Time, In Full) — a delivery-performance measure of orders that arrive both on schedule and complete.
• Bullwhip effect — small changes in consumer demand create increasingly large swings in orders upstream in the supply chain.

Transport and freight

• FTL / LTL — full truckload versus less-than-truckload shipments.
• FCL / LCL — full container load versus less-than-container load.
• CFS (Container Freight Station) — a facility where cargo is consolidated or deconsolidated.
• 3PL and 4PL — third-party logistics providers run logistics operations for a company; a fourth-party provider coordinates several 3PLs and the overall design.
• Incoterms — standard trade terms (such as EXW, FOB and CIF) defining who pays for freight and bears risk at each stage of an international shipment.

India-specific context

Indian logistics questions tend to cite policy and infrastructure: the GST e-way bill for goods movement, the National Logistics Policy (launched in 2022), the PM Gati Shakti infrastructure-planning platform (2021), the Dedicated Freight Corridors, the Sagarmala port programme and FASTag for electronic toll payment.

Look-alike terms to keep apart

1. FIFO vs FEFO — arrival date versus expiry date.
2. MRP vs DRP — manufacturing inputs versus distribution replenishment.
3. ASN vs PO — a purchase order is the buyer's request; the ASN is the supplier's shipment notice.
4. FTL vs FCL — trucks versus containers.
5. WMS vs ERP — location-level execution versus company-wide records.
6. Cross-docking vs put-away — skipping storage versus placing into storage.

How to prepare

1. Build flashcards in three decks: systems and standards, warehouse operations, planning formulas. Test the abbreviation → definition and the reverse.
2. For each term, add one real-world example ("FEFO — milk, vaccines") so the definition has a scene attached.
3. Practise the two formulas (reorder point, EOQ) until you can state them in words.
4. Skim the look-alike list above immediately before you play.

Put it into practice

Try the Supply Chain quiz and keep a list of any term you had to guess — those are your next flashcards.