Wikipedia:Splat tables

Splat tables are tables that are splattered onto pages with little or no formatting. The two most common forms of splat tables are overwide tables which spread columns far across a page and overnarrow tables which scrunch data into a narrow mass with cramped spacing. However, another form of splat table is a headless table which has no column headers.

Overwide tables
The most common of the splat tables are the overwide tables which spread columns far across a page, and scatter the data lists so far apart that the related items are difficult to cross-compare unless grid lines are used to herd the data into common channels. The result of widening tables to the far horizon often resembles old computer printouts which had color-coded ledger lines to track across the related line.

Overnarrow tables
Another common form of splat tables are the overnarrow tables which jumble data into a narrow mass with cramped spacing. The effect of tables which squeeze data into consecutive spaces can cause the wording to seem to run together, unless box lines are used to separate the words. For tables with many columns, the pressure to cram data together might overshadow the option to simply remove some minor data, or combine multiple items into fewer columns.

Tactics to balance tables
In general, try to maintain a reasonable gap between table columns, with the width selected to fit the relative amount of data being presented. For tables of 3 columns, a gap of 14-24 spaces between columns often provides a sufficient separation but keeps columns close enough for comfortable viewing. In most cases, the width should be automatic, or specified in pixels or ems, rather than as xx% percentage widths which tend to spread columns severely on wider screens. The worst option is "width 100%" which almost guarantees the table will be spattered across a wider screen as data is scattered far and wide.

To display many columns of data, always consider omitting the minor data, or perhaps combine related items into fewer columns. With numerous columns, the table can be formatted with box-line separators by using the option "border=1" for class=wikitable, at the start of the table.