The line Tōkyō - Atami is offically a part of Tōkaidō Hon line. However, the line consists of several services using their own tracks. They are:

Keihin-Tōhoku line has its own double track between Tōkyō and Yokohama and is the only service stopping at all stations along the line. (Marked in the Notes column as "KH"). Between Higashi-Kanagawa and Yokohama are the Keihin-Tōhoku tracks also used by Yokohama line trains.
Traffic pattern: Keihin-Tōhoku line and Yokohama line

Yamanote line has its own double track between Tōkyō and Shinagawa. On that section, it is only Yamanote (Marked in the Notes column as "Ya") and Keihin-Tōhoku services that stop at all stations.
Traffic pattern: Yamanote line.

Yokosuka line is a double track line running completly separate from the other services between Tōkyō and Ōfuna.
At Tōkyō station, it uses an underground station connected with Sōbu line, not the normal overground station.
Tōkyo - Shinagawa: Underground (the other services run overground), stopping only at Shimbashi.
Shinagawa - Tsurumi: Runs on a section of the Tōkaidō line called Hinkaku line, serving Nishi-Ōi and Shin-Kawasaki instead of Kawasaki. No platform at Tsurumi station.
Tsurumi - Ōfuna: Parallel with Tōkaido Hon tracks. Two stations are only served by Yokosuka trains (Notes: "Yo only")
Between Nishi-Ōi (on Hinkaku line) and Ōfuna is the Yokosuka line tracks also used by Shōnan-Shinjuku line service.
Traffic pattern: Yokosuka line and Shōnan-Shinjuku line

Tōkaido Hon line itself has a double track used by services as listed in the Traffic Pattern section below.

Tōkaido Freight line (Tōkaidō Kamotsu) is a double track line that runs from Tsurumi to Odawara. Between Tsurumi and Higashi-Totsuka (16.0 km) it has its own route, bypassing Yokohama, and between Higashi-Totsuka and Odawara it runs in parallel with the Tōkaido Hon tracks, but with platforms only at a few stations. The freight line tracks are used by a few non-stopping passenger services (4 southbound and 8 northbound/day).

The traffic pattern below shows only trains running on Tōkaidō Hon or Tōkaido Freight line tracks. Trains running on Keihin-Tōhoku, Yamanote or Yokosuka line tracks are shown at those line's own pages.