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< Productivity Glossary
Calendar Services

What are calendar services?

Calendar services are the primary calendar account for your schedule, forming the backbone and engine for your scheduling and calendar applications. While there are numerous calendar apps available, the services behind them are fewer in number. Here are the most prominent calendar services on the market:

  • Google Calendar
  • Outlook Calendar
  • Apple Calendar

However, there are also open-source alternatives like Fastmail and Proton Calendar, offering similar functionalities.

These services give you all the infrastructure needed to create, update, delete, and read calendar events. As such, they can be thought of as databases containing all the metadata (e.g., dates, times, descriptions, titles) required for calendar events. 

How do calendar services technically work?

Calendar services operate by providing you a basic calendar to schedule and plan your  time. They also serve as the backend infrastructure for add-on calendar apps, while also offering a suite of APIs to facilitate the management of events. Let's take a closer look at how they work:

1. Backend infrastructure

At the core of calendar services lies a robust backend system that stores and manages all calendar-related data. This includes information about events, such as dates, times, descriptions, and participant details. The backend infrastructure allows for the smooth operation of calendar functionalities, handling tasks like data storage, retrieval, and synchronization across different devices.

2. API integration

Calendar services expose a set of APIs that allow developers to interact with the underlying functionality programmatically. These APIs provide endpoints for various operations, enabling developers to integrate calendar features into their own applications or services. Through API integration, developers can leverage the capabilities of calendar services to enhance their products with scheduling functionalities.

3. Authentication layer

To guarantee security and user privacy, calendar services incorporate an authentication layer. This layer authenticates users and authorizes access to their calendar data. Through authentication mechanisms like OAuth, users can grant permission for third-party applications to access their calendar information securely. This authentication layer also facilitates the connection of calendars to various platforms and applications.

4. Direct interaction

Users can interact directly with their calendar service without using a dedicated calendar application. This is made possible through direct API calls, allowing users to perform actions like creating, updating, or deleting events. Direct interaction with calendar services provides users with flexibility and control over their calendar data, enabling customized integrations and workflows tailored to their specific needs.

Examples of popular calendar services

The calendar service landscape is dominated by the three main players: Google Calendar, Outlook Calendar, and Apple Calendar, each offering a comprehensive suite of scheduling tools and features.

  1. Google Calendar: Google Calendar is a widely-used calendar service that offers a range of features, including event creation, scheduling, reminders, and integration with other Google services like Gmail.
  2. Outlook Calendar: Part of the Microsoft Outlook suite, Outlook Calendar provides users with robust scheduling capabilities, email integration, and collaboration features. It's commonly used in business settings and integrates seamlessly with other Microsoft Office applications.
  3. Apple Calendar: Formerly known as iCal, Apple Calendar is the default calendar application for Apple devices such as iPhones, iPads, and Mac computers. It offers features like event creation, synchronization across Apple devices via iCloud, and integration with other Apple services.

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