Accounting software describes a type of application software that records and processes accounting transactions within functional modules such as accounts payable, accounts receivable, general ledger, payroll, and trial balance. It functions as an accounting information system. It may be developed in-house by the organization using it, may be purchased from a third party, or may be a combination of a third-party application software package with local modifications. Accounting software may be on-line based, accessed anywhere at any time with any device which is Internet enabled, or may be desktop based. It varies greatly in its complexity and cost.

The market has been undergoing considerable consolidation since the mid-1990s, with many suppliers ceasing to trade or being bought by larger groups.

Personal Accounting : Personal accounting software is mainly targeted towards home users, supporting accounts payable-type accounting transactions, managing budgets, and simple account reconciliation, at the inexpensive end of the market.

Low-end market : At the low-end of the business markets, inexpensive applications software allows most general business accounting functions to be performed. Suppliers frequently serve a single national market, while larger suppliers offer separate solutions in each national market.

High-end market : The most complex and expensive business accounting software is frequently part of an extensive suite of software often known as enterprise resource planning (ERP) software.

These applications typically have a very long implementation period, often greater than six months. In many cases, these applications are simply a set of functions which require significant integration, configuration and customization to even begin to resemble an accounting system. The advantage of a high-end solution is that these systems are designed to support individual company specific processes, as they are highly customizable and can be tailored to exact business requirements. This usually comes at a significant cost in terms of money and implementation time.