What is solvent effect in GC?

The higher boiling solvents are condensed in the column head, while the lower boiling solvent peak vaporizes and moves far apart from the higher boiling component. This is called as solvent effect, which causes the analyte to focus as sharp band in the head of the column while separates them away from the solvent peak.  In order for the solvent effect to be effective in a, the starting oven temperature of the column should be closer to the boiling point of the solvent. This peak focusing phenomena causes the peaks to be sharper