html The hypertext markup language, commonly referred to as HTML is at the backbone of the internet and World Wide Web. It is the standard markup language used in the creation of webpages and was released in 1993 at the advent of the internet. The format defines the structure and layout of a webpage through markup tags such as header tags and image tags from which a browser can interpret multimedia information for on screen presentation. To view files and webpages saved with the .html filename extension, one needs a compatible web browser that implements the HTML specification. Because the format is open source, several browsers which are mostly free to use can open such files. The World Wide Web consortium actively maintains and updates the html specification.
xlsx The .xlsx is an open source filename extension format developed by Microsoft in collaboration with ISO/IEC and ECMA. It is part of the Open Document family of file formats. The .xlsx is associated with spreadsheet authoring applications particularly with Microsoft's Office Excel 2007 and above. The format has existed since 2005 and is also supported by several other proprietary and open source spreadsheet authoring software other than Microsoft's Office Excel. The xlsx format is the default filename extension for all spreadsheet documents produced using Microsoft Office Excel 2007 SP2 and above.