If someone is seen online does that mean they have opened our conversation or any conversation on whatsapp? When you open a conversation on whatsapp and the contact is seen as online have they opened your conversation or just any conversation?
You can read from the WhatsApp FAQ:

What does &quot;last seen at...&quot; and &quot;online&quot; mean exactly?
&quot;online&quot; means that contact has WhatsApp open and is connected to the internet. However, it does not necessarily mean they have read your chat.

That clearly stats that a contact with &quot;online&quot; status just needs to have the app opened within an active Internet connection.