Chatter in Salesforce.

Hi Anjali,
In Salesforce and the Salesforce app, Chatter is enabled by default. Configure various Chatter features and customize the Chatter experience for your users on the Chatter Settings page in Setup.
To access the Chatter Settings page in Setup, enter Chatter in the Quick Find box and select Chatter Settings.
To disable Chatter for your entire organization, deselect Enable in the Chatter Settings section.