Practical Transformation Using XSLT and XPath (5-hour free preview; 24 hours total)

Python is a general-purpose programming language that became the standard interface for driving numerical and machine-learning code written in other languages.

Git is a distributed version control system that records the history of a set of files as a graph of snapshots, lets many people work on branches of that history at once, and merges their work back together.

HTTP is the request-and-response protocol of the web: a client sends a method, a path and headers, a server answers with a status code, headers and a body, and each exchange stands alone unless the two sides agree to carry state in a header.

Caching keeps the result of expensive work, such as a rendered page or a database query, and serves that stored copy until it expires, making it the largest single source of speed on any busy website.

Uptime is the proportion of time a service answers requests, quoted in nines, and a service level agreement is the contract clause setting out how that proportion is counted and what the provider owes when it falls short.

Shared hosting puts your website on a machine that is simultaneously running hundreds of other people's, pooling its processor, memory and disk between all of you, which is both why it costs so little and why your speed partly depends on strangers.