CS8025 error

i have been using bits and pieces from burgzergarcade’s hack and slash tutorials and i have recently done my modifiedStat script but there is an error (CS8025):

Assets/Ascripts/!Character/Charcter classes/ModifiedStat.cs(6,17): error CS0246: The type or namespace name `List’ could not be found. Are you missing a using directive or an assembly reference? i copied nearly exactly

using System;
using System.Collections.Generic;

public class ModifiedStat : BaseStat {

	private List _mods; //A list of Attributes that modify this stat

	private int _modValue; //The amount added to the baseValue from the modifiers

	public ModifiedStat() {
    	_mods = new List<ModifyingAttribute>();
    	_modValue = 0;
	}

	public void AddModifier( ModifyingAttribute mod) {
    	_mods.Add(mod);
	}

	private void CalculateModValue() {
    	_modValue = 0;

    if(_mods.Count > 0)
       	foreach(ModifyingAttribute att in _mods)
         	_modValue += (int)(att.attribute.AdjustedBaseValue * att.ratio);
	}

	public new int AdjustedBaseValue {
       get{ return BaseValue + BuffValue + _modValue; }
	}

	public void Update() {
    	CalculateModValue();
	}
	
 
	public struct ModifyingAttribute { public Attribute attribute; public float ratio;

	public ModifyingAttribute(Attribute att, float rat) {
    attribute = att;
    ratio = rat;
	}
	}
}

help please

List is a generic, it requires a type to be specified. The type specified is the type that is contained in the List Collection.

using System;
using System.Collections.Generic;

public class ModifiedStat : BaseStat {

    private List<ModifyingAttribute> _mods; //A list of Attributes that modify this stat

    private int _modValue; //The amount added to the baseValue from the modifiers

    public ModifiedStat() {
        _mods = new List<ModifyingAttribute>();
        _modValue = 0;
    }

    public void AddModifier( ModifyingAttribute mod) {
        _mods.Add(mod);
    }

    private void CalculateModValue() {
        _modValue = 0;

    if(_mods.Count > 0)
        foreach(ModifyingAttribute att in _mods)
            _modValue += (int)(att.attribute.AdjustedBaseValue * att.ratio);
    }

    public new int AdjustedBaseValue {
       get{ return BaseValue + BuffValue + _modValue; }
    }

    public void Update() {
        CalculateModValue();
    }


    public struct ModifyingAttribute { public Attribute attribute; public float ratio;

    public ModifyingAttribute(Attribute att, float rat) {
    attribute = att;
    ratio = rat;
    }
    }
}