200 or 300 gsm sketchbook - which weight I should choose?

Comparison of 200gsm and 300gsm sketchbook. What does GSM means? How to find right weight of paper.

Strathmore 300 Series Sketch Paper Pad, Top Wire Bound, 5.5x8.5 inches, 100 Sheets (50lb/74g) - Artist Sketchbook for Adults and Students - Graphite, Charcoal, Pencil, Colored Pencil

Sketchbook Reviews Round-up - Ingrid Hill Art

Paper weight: What does it mean? - Strathmore Artist Papers

100% Cotton 300gsm Heavy Weight Watercolor Paper: its an ideal medium for a variety of artistic techniques, its cold-pressed texture makes it perfect

tumuarta Watercolor Sketchbook, 4x6”, 140 LB, 300 GSM, 100% Cotton Paper, Cold Press, 24 Sheets, 48 Pages, Watercolor Journal for Use As Travel

Watercolor Pad 9X1,140lb/300g, Professional Choice –

Moleskine Folio A4 Watercolor Album (11.75 x 8.25)

How To Choose A Sketchbook – Cowan Office Supplies

Watercolour paper explained

Strathmore 200 Series Sketch Pad, 50 lb., Acid-Free Paper, 9 x 12, 100 Sheets