NCBI site users are not required to establish an account to gain access to the NCBI databases and other services, such as BLAST ®. You can conduct your searches and access our database records even if you are not logged in to NCBI. However, registering for a (free) NCBI account will enable you to use the My NCBI tool and customize the tasks you wish to accomplish with NCBI web resources. For example, creating email alerts for your searches is just one of the many features of My NCBI.
Nearly all types of sequences and molecular data submissions require submitters to log in. Furthermore, NIH-funded investigators use NCBI accounts/My NCBI to manage their compliance with the NIH Public Access Policy.