Are you confused about open data jargon? 
Here is a list of commonly used terms which you might hear or read about.
Bar graph - A bar graph or chart uses horizontal or vertical bars whose lengths proportionally represent values in a data set. A chart with vertical bars is also called a column graph or chart.
Data - Facts and statistics collected together for reference or analysis.

Data Aggregation - Combining information and expressing it in a summary form. For open data combination is usually done for numerical data based on measures like count, sum or averages.

Dataset - A dataset is an organized collection of data. The most basic representation of a dataset is data elements presented in tabular form. Each column represents a particular variable or dimension. Each row represents one instance of the type of information in the dataset.

Dimension - Column values of a dataset which can be aggregated to show specific information.  A dimension is a field that orders, groups, or categorizes your data, such as dates and categories.  The dimension is often shown on the x-axis of a graph or as points on a map.  You will be presented with dimension when using the visualization tool.

Filtering - Refining information in a dataset based on a condition.  Data filtering will involve taking out information that is not important to you.

Geospatial - Used to indicate data that has a geographic component to it. This means that the records in a dataset have location information tied to them such as coordinates, address, city, or zip code.

Heat map - A heat map (or heatmap) is a graphical representation of data of individual values contained in a dataset table which are represented as colors.  The use of colors indicate the level of activity (or the concentration of activity), usually using darker colors to indicate low activity, and brighter colors to indicate high activity.  For example, a heatmap could be used to represent the number of foreclosures in a geographical area during a certain period of time.  Heatmaps are usually interactive representations that adjust depending on how much you zoom in or out in a heatmap. 

Metadata -  It is “data that describes data.” Metadata describes a number of characteristics or attributes of data. Metadata may describe how a dataset is represented, last time updated, owner, ranges of acceptable values, its label, and its relationship to other data. Metadata also may provide other relevant information, such as the responsible steward, associated laws and regulations, and the access management policy.

Measure - A measure is a numeric field such as a sum, average or any calculation such as the count of rows associated with a selected dimension.  You will be presented with measures when using the visualization tool.

Open Data - Making data that belongs to the public broadly accessible and usable by humans and machines, free of any constraints.

Pie Chart - A circular graph divided into sectors, each with an area relative to the whole circle, and is used to represent the frequency of values in a dataset.

Point Map -  A map which shows geographical information using points like location of schools, police stations etc.

Region MapA map which shows aggregated information for a bounded geographical area like a zip code, council, county or state.

Socrata - The information technology company that hosts dataMontgomery open datasets and provides tools data manipulation and sharing.

Sorting - Arranging data systematically in ascending or descending order according to a dimension or measure.

Visualization - Visual representation of information in a dataset using graphs, charts or maps.  The process by which data are visualized, or presented, after the data cleaning process, involves making choices about which data will be visualized, how data will be visualized, and what message will be shared with a target audience.