LDAP stands for Lightweight Directory Access Protocol. It is an application-level protocol that allows queries about a directory service to search for information.

LDAP defines the way to access that directory, that is, it is optimized to carry out read operations on the directory, such as validating authenticated access to a user stored in the directory.

A directory service runs the client-server model, so if a client computer wants to access the directory, it does not access the database directly; instead contacts a process on the server. The process queries the directory and returns the result of the operation to the client. Among the main terms when we work with LDAP, let's highlight the following:

• Classes: The objects and their characteristics are defined in classes. For example, the type of object to be defined and the attributes that it will contain depend on the type of object. In the scheme, each class is defined with the attributes that will be obligatory and optional for each created entry.
• Objects: Entries in the directory. Objects are instances that are created from a certain class or several, depending on the attributes required for an object. The entire directory will be composed of objects (such as users, groups, or organizational units).
• A directory service is like a database where we organize and store information with objects of different classes. This hierarchically-organized structure of the objects is achieved with the implementation of LDAP.
• entry: A unit in an LDAP directory. Each entry is identified by its unique distinguished name (DN).
• DN: The distinguished name to uniquely identify a specific object in the directory. That is, each entry defined is unique throughout the directory. As we can see, the DN of that object (user type) will be unique throughout the directory and will uniquely identify you.
• Attributes: Pieces of information directly associated with the input. For example, an organization can be represented as an LDAP entry. The attributes associated with the organization can be your fax number or your address, for example. In an LDAP directory, the entries can also be people, with common attributes such as their telephone number and email addresses. Some attributes are mandatory while others are optional.
• The LDAP Data Exchange Format (LDIF): An ASCII text representation of LDAP entries. The files used to import data to the LDAP servers must be in LDIF format.