Data & Transformation
How raw data gets cleaned, reshaped, and turned into something useful
Aggregation
beginnerCombining many individual data points into a summary. Aggregations answer questions like 'how many,' 'what's the total,' or 'what's the average' by collapsing a list of values into a single result.
Data Pipeline
intermediateAn automated flow that extracts data from a source, transforms it into a useful shape, and loads it into a destination. Often called ETL (Extract, Transform, Load). Data pipelines run on a schedule to keep dashboards, reports, and databases up to date.
Deduplication
intermediateRemoving duplicate entries from a dataset so each record appears only once. Duplicates creep in when data is imported from multiple sources, forms are submitted twice, or syncs overlap. Deduplication keeps your data clean and your counts accurate.
Normalization
intermediateRestructuring data to reduce duplication and inconsistency. Instead of repeating the same information in multiple places, normalization splits data into related tables or structures and connects them with references.
Null Value
beginnerA special placeholder meaning 'no data here.' Null is different from zero, an empty string, or false. Those are all real values. Null means the value is deliberately absent or unknown. Forgetting to handle null is one of the most common sources of bugs.
Parsing
beginnerReading raw text and extracting structured information from it. Parsing turns unstructured data (a string, a file, a response body) into something your code can work with: objects, arrays, numbers, dates.
Schema
beginnerA blueprint that defines the expected shape of your data: what fields exist, what types they are, and which ones are required. Schemas catch bad data early by rejecting anything that doesn't match the expected structure.
Transformation
beginnerConverting data from one format or structure into another. Transformations reshape data so it fits where it needs to go: renaming fields, changing date formats, flattening nested objects, or combining multiple sources into one.
Validation
beginnerChecking that data meets expected rules before using it. Validation is a safety gate: it catches typos, missing fields, wrong types, and out-of-range values at the boundary, when data enters your system, rather than letting bad data cause mysterious failures later.