The master pages define the unchanging design elements of a SharePoint site. Put another way it determines the layout, styles, scripts, fonts, and images that are identical for every page type.
In SharePoint 2013 there are 2 default master pages, rather than only the 1 that was available in SharePoint 2010. The default master pages in SharePoint 2013 are named oslo.master and seattle.master. It is possible to view these master pages in a publishing site by navigating to the ‘Settings’ gear icon in the top right corner of your site, then ‘Site settings,’ and under ‘Web Designer Galleries’ click ‘Master pages and page layouts.’
Now let’s see how to set the master page for a publishing site. If you are on another type of site template first activate the publishing feature at the site collection level and site level.
Next navigate to the ‘Settings’ gear icon, then ‘Site settings,’ and under ‘Look and Feel’ click ‘Master page.’ You should see a screen with options similar to those below.
Firstly, notice that there are two master page configurations, the site master page and system master page.
Site Master Page
The site master page is used by all publishing pages, or pages that visitors to your website can see. It allows for the customization of publishing pages differently than system pages, and also allows for a different master page to be displayed to different devices using device channels. It is not used by any other page by default. Though it is possible to edit the master page using SharePoint Designer, it is not recommended unless absolutely necessary.
System Master Page
The system master page is used by SharePoint everywhere the site master page is not, including administrator pages, lists, and document library views. Be very careful customizing this page as it is used extensively throughout all SharePoint sites.
To see the differences between these two master pages we will set ‘oslo’ as site master page, and ‘seattle’ as system master page.
This is what seattle.master looks like when applied to a system page:
Next, let’s navigate to a site page to see what oslo.master looks like:
A basic difference that can be immediately noticed is the left navigation menu has changed. It is recommended that you experiment with these master pages by altering their settings, and adding different web parts and contents to pages.
There is a new feature in SharePoint 2013 that allows for the creation of a new master page from an existing HTML page. This is a drastic change from master page customization in SharePoint 2010 and has been a huge relief to SharePoint designers and power users.
First, navigate to the ‘Settings’ gear icon, then ‘Site settings,’ and under ‘Look and Feel’ click ‘Design Manager.’
Design Manager should look like the following with a Welcome message, a few recommended options, and a navigation bar on the left side.
Click ‘Edit Master Pages’ link and choose ‘Convert an HTML file to a SharePoint master page.’
Then click ‘Add a new item’ and upload your chosen HTML page. SharePoint 2013 will take this HTML page and convert into an ASP.NET master page automatically.
After the conversion is done you will be able to view your new master page in the ‘Edit Master Pages’ section of Design Manager.
You can then set this new master page as either a site or system master page. As can be seen Design Manager in SharePoint 2013 allows for very high levels of customization by power and non-power end-users alike. Try it out, maybe you’ll like what you end up seeing!