As standard, the default setting to view your contacts is by 'Person' mode.  

This means that every person is shown whether they are a contact at a company or just an individual person such as in a business to consumer environment - as shown in the screenshot below: 

You can view your contacts by 'Organisation' mode or 'Person' mode by toggling between the two icons as shown below in red: 

To view contacts by 'Organisation' please click on the 'Organisation' icon to filter your contacts as shown below in red: 

To switch back to seeing all contacts such as people contacts at companies and as individuals just click on the 'Person' icon as shown below: 

You can use the above filters to switch between 'Organisation' mode and 'Person' mode. 

Admin Users can change their 'default' view of contacts to display always in 'Organisation' mode.  To set this up go to the Settings icon as shown below: 

Next click on the Global Settings tab and select the checkbox 'Organisations first?' and click on 'Update Settings' as shown below:

When you next view your contacts your default view will now be in 'Organisation' mode as shown below: