While dealing with clients there might always be Instances where you might need to give access for Information sharing. As we all know that company Information can be confidential and it wouldn’t be appropriate to give an external user access to the whole site.
In this case what we could do is to create a separate site collection in SharePoint. And then use the SharePoint feature to give that user access. By creating a new site collection, we are ensuring that he gets access to that space only. And we can control his access in this site too, but setting different permission levels like Read only, Editor or subscriber to name a few.
One must note that once you click on the SharePoint button, an Invitation will be sent to the user. Now in order for that person to access the site, the email ID should be a Microsoft account. In case the account is not of Microsoft, it can be made one by filling up this form https://signup.live.com/?uaid=dd299f8c46e94abba1c1d15c4f6da9dd&lic=1 . Make sure to make the username as your current email address. Once the account has been created, the user can login with the same ID.