If you are new to Tableau development you may just enter a Title for your dashboard in the header. Did you know there are lots of other helpful items you can include in the header?
Does your team have a brand or icon that you can include so users can know it was developed by your team? This is a great opportunity to build a team portfolio of dashboards. I have an icon linking to my blog site in a Tableau Public dashboard here. I also have it linking to a previous blog article that the dashboard was used for.
Email Icon / URL Action
What if your client has a question about a specific metric on your dashboard. Or what if your dashboard is missing data? I recommend including an email icon with a built in Mail to action. (I use icons8.com for my icons.) You can add a header for your email that is specific to the dashboard. This is also helpful if the client has any suggestions for the dashboard. Andrew Watson from TAR Solutions has a great blog article on how to do this here.
As of Date or Data Refresh Timestamp
It is important for your clients to know the last date the data was refreshed. I recommend putting an As of Date in the header or footer of a dashboard. Here is a link to a Tableau Help page on how to add this field.
Data Date Range
Another good idea is to list the date range of the data used in the dashboard. This will help explain the seasonality or provide an overview of time detail. Some users like to put this in a footer instead of a header.
Who Created the Dashboard?
Some users like to enter who created the dashboard in a header or footer. I do not recommend this as it may change when someone makes an update. It can get visually busy if you have a team of users who are making updates. I like to add a sheet that has the details for creation, when it was updated, and by whom.
Did you know you can use the FullName() formula and it will return the users full name? Some people like to put this in a header as a welcome banner. This may not work depending on how your server is set up. Here is a link to all of the Tableau User functions/formulas.
Ken Flerlage of the Flerlage Twins site lists eight different examples of Legends in the header of a dashboard here. This can promote interactivity/client engagement in your dashboard.
Show the Filtered Selections and Values
Some users like to save visual real estate of a dashboard by placing filters in a collapsible container. A disadvantage of this is that the user will have to open the container again to see how they filtered the dashboard. Some developers like to show the caption of the dashboard for quick reference to show the user what they have filtered it by. You have to go to the Worksheet menu and select Show Caption. Then on the dashboard, you have to make sure it also displays there. Here is the help article (link) on how to do this. (Ken Flerlage also helped in this one!)