Instant messaging (IM) is a type of online communication that allows users to send and receive messages in real-time. Instant messaging services are incredibly popular, as they provide a quick, easy way to keep in touch with friends, family, and colleagues.

The most popular instant messaging services are considered to be universal, meaning they can be used across different platforms (such as mobile devices, computers, and tablets). The following are some of the most widely-used universal instant messaging services:

• WhatsApp is a cross-platform messaging app available for both Android and iOS devices. It allows users to exchange messages, photos, and videos with individual contacts or within groups. WhatsApp also offers voice and video calling.
• Viber is a cross-platform messaging app that allows users to send text messages, photos, videos, and audio messages to other Viber users. It also provides voice and video calling.
• Facebook Messenger is a messaging app that allows users to send and receive messages, photos, and videos with their Facebook contacts. It also offers video calls.
• Telegram is a cloud-based messaging app for both Android and iOS platforms. It allows users to share messages, photos, and videos with other Telegram users, as well as to create group chats.
• WeChat is a messaging app for both Android and iOS devices. It combines the features of a messaging app with a social media platform, allowing users to send messages, photos, videos, and audio messages to other WeChat users.

These universal instant messaging services provide an easy and convenient way for users to stay in touch with people around the world. All of them offer various features, such as voice and video calling, which can be used to hold conversations with multiple people at once. Ultimately, the best service to use will depend on the user’s needs and preferences.