= Condensed structural formula
A \b[condensed structural formula] writes connected groups of <chemical atoms> compactly, omitting some explicit bond strokes. It preserves interpretable connectivity information, unlike a <molecular formula> that merely totals the atoms. It is one way to represent a <structural formula>, whose purpose is to describe how atoms are connected.<IUPAC Compendium of Chemical Terminology, fifth edition (Gold Book) by International Union of Pure and Applied Chemistry>[Entry S06061, structural formula: connectivity information; DOI10.1351/goldbook.S06061.]{ref}
For an original counting example,
$$
\mathrm{CH_3(CH_2)_4CH_3}
$$
can be unrolled as $\mathrm{CH_3CH_2CH_2CH_2CH_2CH_3}$. The two terminal groups supply two carbons and six hydrogens; four interior groups supply four carbons and eight hydrogens. Thus the <molecular formula> is $\mathrm{C_6H_{14}}$, since $2+4=6$ and $6+8=14$. The parentheses abbreviate a connected repeated group, rather than introducing a separately floating <molecule>.
The compression must be interpreted with the chosen convention. A formula such as $\mathrm{CH_3CH_2OH}$ specifies different connectivity from $\mathrm{CH_3OCH_3}$ despite their common atom counts. Neither expression by itself gives every bond angle or a unique three-dimensional conformation; those questions involve <molecular geometry> and <stereochemistry>.
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