What types of watercolor pens are there?

Children's Stationery Watercolor Pens
These watercolor pens are designed specifically for children's drawing and writing, offering vibrant colors and ease of use. They typically fall into the following categories:
Single-color pens: The most basic style, each pen contains only one color of ink. The barrel, nib, and refill are simple, making them suitable for everyday doodles and basic line drawing.
Two-color pens: The nib and refill are separated into two parts, allowing for simultaneous writing of two colors. The strokes create a layered and three-dimensional effect, making them ideal for calligraphy, decorative painting, or children's calligraphy practice, inspiring creativity.
Multicolor pens: Three or more refills are embedded in a single nib and secured by injection molding. These pens can each write in different colors without mixing, making them ideal for art studios, teachers giving lectures, or when switching between multiple colors quickly.
Features: Most pens have plastic barrels filled with sponge for water storage. While affordable, they have limited ink capacity and are not suitable for large-format drawing. Some styles also have wooden nibs, so be careful with pressure to avoid damage.

Professional Fine Art Watercolor Brushes
These brushes are designed specifically for watercolor painting, emphasizing absorbency, elasticity, and expressive brushstrokes. Common types include:
Round-point brushes: These brushes have a soft, rounded tip and a tightly gathered tip. They are ideal for outlining lines, blending gradients, detailing, and applying color to large areas. They are the most commonly used basic brush type in watercolor painting. They come in a variety of sizes (e.g., #000 to #30), with small sizes for detailed delineation and large sizes for quick application.
Flat-point brushes: These brushes have a flat, rectangular tip with a clean edge. They are suitable for creating strong straight lines and regular shapes (such as buildings and geometric figures). They can also be used with the side of the brush to create fine lines or rough textures. They are often used for sketching, applying base color, or depicting clearly structured objects.
Fan-point brushes: These brushes have a fan-shaped tip, combining the characteristics of flat and round-point brushes. They are ideal for creating textures such as fluffy grass, bushes, hair, or feathers, creating natural, layered strokes. Mop Brush: Large bristles, excellent water retention, and a rounded, slightly pointed tip. It's primarily used for quickly applying base color to large areas or creating soft gradients. The tip can also be used to add detail, perfect for creating a fluid or moist atmosphere.
Pointed Brush (Liner): Long, sharp bristles with excellent elasticity. Used for precisely outlining fine details like hair, leaf veins, edges, or highlights, requiring precise control.
Chicken Spur Brush: A traditional watercolor brush with a full body and a slender tip (similar to a chicken's spur). It combines color application with detailed detail, making it suitable for traditional techniques or scenes requiring delicate transitions.
Paper Brush: A flat, wide brush head, similar to a brush, is used for quickly applying damp paper, applying background color, or applying water evenly when mounting paper. It's an essential tool for large-scale paintings or background processing. Special function pens: such as oval pens (cat tongue pens), the bristles of which swell and gather after being soaked in water, suitable for drawing fine and tight lines or textures; hazelnut pens (a modified version of the commonly used pen shape in oil painting), with good elasticity, are suitable for mixed media or heavy texture expression.