Alexa is a competitor intelligence and website analytics software that provides actionable SEO insights based on a sample of data from the web. Alexa enables users to view audience demographics, engagement, traffic trends, keyword research, traffic sources, and website comparisons.
SEMrush is a marketing toolkit designed for digital marketing professionals, with tools for optimizing strategies across SEO, PPC, social media, content and PR.
Hypertext Markup Language (HTML) is the standard markup language for documents designed to be displayed in a web browser. It can be assisted by technologies such as Cascading Style Sheets (CSS) and scripting languages such as JavaScript.