* Software maintenance is known as the process by which programs are updated, new tasks are included, program bugs are corrected, and programming problems are solved in the form of maintenance contracts concluded by programming companies with their customers, and are calculated as annual fees based on a percentage of the total cost of the program  ,

 * There are four types of software maintenance, and they are as follows:

 1- Adaptive maintenance: It comes as a result of internal changes to the organization’s software systems, such as moving programs to new devices, or to translators and other operating systems, in order to adapt to external requirements, and keep pace with modernity, in meeting the needs of the user and business sectors.

 2- Corrective Maintenance: The process of modification and improvement of defect problems in systems and programs is the essence of corrective maintenance work, so that the program instructions, program structures, and program alerts are modified, and either the need for them comes from the user or from the error reports that appear in the programs, then the fix  Either for emergency failures, or a scheduled process for adjustment and correction.

 3- Preventive maintenance: in which programs are restructured, so it is called software re-engineering, with the aim of preventing software problems in the future, so that programs become more understood, their features improve, and thus easier to maintain.

 Optimal maintenance: They are additional modifications to the programs to remain usable for the longest possible period, which reduces the costs of use and maintenance, increases its speed, reliability, and provides it with new features.

 The need for software maintenance appears due to the following circumstances and factors:

 1- Market changes and the policies followed, as new laws are being introduced on institutions, such as changing tax systems and accounting processes, which requires modifying programs.

 2- Customer requirements, as the client is always required to amend the settings for his work, and add new features to his programs.

 3- Changes of programs or host devices, in the event that any of the hardware or operating systems are changed, it is natural to change the software architecture to adapt to it.

 4- Adjustments to the levels of organizational work, as it sometimes requires organizations to make organizational changes, which calls for amending their programs.

 * The software maintenance process includes the following steps:

 1- Determine the requirements for change in the programs, by recording the observations or the wrong messages that are issued from them.

 2- Analyzing the modification of the software, including the security and integrity of the system, and in the event that the modification is costly, then another alternative is searched.

 3- Designing new procedures that need modification, by testing them and making sure of their effectiveness.

 4- Implementing the new code for the units that were designed in the previous stage, so that every programmer is required to test the programmed unit, in parallel with other units.  An integrative test of the new units with the system as a whole.

 5- Delivery and deployment of the system throughout the organization, and the final test is conducted in the company after the delivery of the program, and if necessary, users are trained on it.