There are multiple ways to generate hair-cards with Hair Tool:

•     Hair System - procedural hair generation based on geometry nodes - great for all kind of complicated hair styles (braids, curls, punk etc)
•     using grid Guide Mesh - where hair strands follow mesh loops - great for modeling: long hair, buns, fringes, eyelashes etc.
•     using Track To Mesh - where hair tips are glued to guide mesh - great for short to medium hairstyles
•     grooming tools - that can be used together with Blender Curve Sculpt mode and procedural effects - Deformers
•     drawing and extending hair strands similar to Grease Pencil drawing - now rewritten to use new hair curves,
•     short hair modeling - for short to medium length hair - animal fur, short human hairstyles. Hair-cards will be spawn from each mesh edge.
•     using shell hair modeling - great for very short hair: fur, carpets. Requires special material (there is UEngine material in HTool docs)

Some of the features:

•     tools for curve based hair modeling (cutting, extending, deforming etc) - rewritten to support new curves
•     automated UV workflow (you can define uv regions, which can then be automatically assigned to hair strand)
•     easy hair rigging and animation with Jiggle physics
•     hair library that contains various hairstyles and sub-components,
•     various adjustable ribbons profiles - Mesh Profile, Curls Profile, Circle, Flat, Braids etc.
•     convert: Curves to Particle Hair, Particle Hair to Curve ribbons, Curve ribbons to mesh ribbons and so on.
•     curve resampling and decimation (increases/decreases curve points count)
•     generating vertex color/weights gradients, transferring UVs and vertex weights from character to mesh haircards.
•     texture baking from new hair curves; supports: normal, ao, diffuse, tangent, ID, root, flow and more maps
•     build-in add-on auto-updater
•     and more

Bit older videos (for Hair Tool 3 - but mostly still valid) showing some hair modeling techniques:

•     hair setup in one minute
•     short hair creation using Shell Hair and Short Hair modeling techniques
•     create hair without grooming