Can I lock down what my employees can see in the CRM

I only want my salespeople to see the contacts and accounts they are assigned to work and not see each others. Can I do that in the CRM?
If you have multiple users connected to your CRM, you can limit them to only be able to see the records they are the owner of.

For example, if you import a list, you can assign that list to have all the records to be assigned to a particular user. This is done on the import page where you can assign records to a user.

Then in the Organization page in Settings, you can change the user's rights so that they can only see records that assigned to them.

This means that they will not be able to see any records that are assigned to another user. So if you have contacts that are assigned to you, they will not see them.