It looks like you are searching about the introduction on the Underscores framework for your WordPress theme development and has arrived here accidentally. But, believe it or not, you have came in the right place to have some information regarding on this framework.
We all, as the theme developer know that there are many WordPress Theme Development framework available nowadays. But, we always prefer the best framework to suit our requirement. One of the best framework available now, is Underscores by Automattic, which is being actively developed day by day and by many of the top level developers as their contributions for the developer who want to develop their theme from scratch.
Importance of Using Framework
So, it might come in your head that, why do we need the framework to develop our theme? Its pretty simple and you may have faced it too already when developing your theme from scratch. If you are developing the themes from scratch, then, you may require too much coding and it may consume time. Also, if you develop the theme using the pre-existed theme, then, there you may be required to remove many codes as the current theme may not have all the features which we are taking as the sample for theme development. So, using the framework will be best for the theme development project. Here, we will be describing about the Underscores Framework, developed by Automattic and its contributors.
Since, WordPress and web is constantly being developed day by day, we may not be able to cope on it in daily basis. But, this framework Underscores, is being maintained day by day as the web and WordPress grows day by day. Also, the functions used in this framework are well documented too, to be familiar with how the function works, and is mostly using the WordPress default function to display the contents while using this framework in the user front-end. So, modification of the code requires less unless you want to build the tough WordPress theme for your project. We see also that from the GitHub official page of UnderScores, it is constantly being developed and being maintained day to day basis. So, using this framework to maintain your project will best suit your need since it contains all of the basic codes required to develop your WordPress themes.
Now, since we already covered the introduction on UnderScores framework, so, now, in order to develop your theme, you need to visit its official website, which is in this link. So, after you visit there, you get the option to add your theme name there and your theme will be instantly downloaded with all of the required basic codes to develop the theme, attached in the downloaded file. So, if you have got the name to your theme and is ready to start developing it, you can add the name in the text box labelled with CREATE YOUR UNDERSCORES BASED THEME and then, by clicking on Generate button. After the download is completed, extract the downloaded file and add it to the WordPress folder containing the theme, ie, wordpress-root-folder/wp-content/themes/ and now you can navigate to Appearance > Themes and your newly downloaded theme will appear in the themes list. Now, you can change it to your liking and either sell it and earn for the living or contribute to the community. It completely depends on your choice.