The Search Button on the top allows you to quickly find and open a specific Project from any page.
On Most of the Pages
Click the Search Button to open the Project drawer where you can search for the Project, go to the Project, edit Project information, etc.
Portfolios Page
On the Portfolio page, click the Search Button to search for the Projects in the current Portfolio.
Project Page
On the Project page, click the Search Button to search for the Tasks in this Project by task name.