In salesforce it is possible to follow accounts and leads. There is a green plus and Follow is written next to it ("Follow this account to receive updates in your feed") and this is visible in accounts and leads on the top right side under the account or lead Name. I was working on someone elses salesforce and the green plus with follow next to it to click to follow is not visible. I tried to find it if in setup to enable it but I haven´t found it so far. Where can I opt it in to see this for leads and accounts?