PHP 7.0 on CentOS/RHEL 6.8 and 7.2 via Yum

PHP 7.0.11 has been released on PHP.net on 15th September 2016, and is also available for CentOS/RHEL 6.8 and 7.2 at Webtatic via Yum.
PEAR installer now supports PHP 7.0, however most pecl libraries will not support it as well without their maintainers adding compatibility, so only pecl libraries that do support it will be in the Webtatic repository.
pecl memcache extension – no sign of PHP 7 support development in official source repository
pecl memcached extension – PHP 7 support is still in development, and no pre-releases available

PHP 7.0.0 comes with new version of the Zend Engine with features such as (incomplete list):
Improved performance: PHP 7 is up to twice as fast as PHP 5.6
Consistent 64-bit support
Many fatal errors are now Exceptions
Removal of old and unsupported SAPIs and extensions
The null coalescing operator (??)
Combined comparison Operator (<=>)
Return Type Declarations
Scalar Type Declarations
Anonymous Classes

To see what else has been added, check out the Migrating from PHP 5.6.x to PHP 7.0.x.
To install, first you must add the Webtatic EL yum repository information corresponding to your CentOS/RHEL version to yum:
CentOS/RHEL 7.x:
rpm -Uvh https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpmrpm -Uvh https://mirror.webtatic.com/yum/el7/webtatic-release.rpm

CentOS/RHEL 6.x:
rpm -Uvh https://dl.fedoraproject.org/pub/epel/epel-release-latest-6.noarch.rpmrpm -Uvh https://mirror.webtatic.com/yum/el6/latest.rpm

Now you can install PHP 7.0’s mod_php SAPI (along with an opcode cache) by doing:
yum install php70w php70w-opcache

You can alternatively install PHP 7.0’s php-fpm SAPI (along with an opcode cache by doing:
yum install php70w-fpm php70w-opcache

See the package list below for additional SAPIs and PHP extensions.
This will install the mod_php SAPI for PHP, however there are other sapis such as php-fpm (via php70w-fpm package). Read on below for more information about the available SAPIs
If you would like to upgrade php to this version it is recommended that you first check that your system will support the upgrade, e.g. making sure any CPanel-like software can run after the upgrade.
Unless you know what you are doing, it is risky upgrading an existing system. It’s much safer to do this by provisioning a separate server to perform the upgrade as a fresh install instead.
If you know what you are doing, you can upgrade PHP by:
yum install yum-plugin-replace yum replace php-common --replace-with=php70w-common

It will likely give you a message “WARNING: Unable to resolve all providers …”. This is normal, and you can continue by tying “y“. You will be given a chance to see what packages will be installed and removed before again being given a chance to confirm.

SAPIs – different runtime environments of PHP
mod_php NTS
(non-thread safety) Contained in the php70w package, this SAPI integrates into Apache Httpd (2.2.* on RHEL/CentOS 6, 2.4.* on RHEL/CentOS 7). It is the standard SAPI for use with httpd prefork mpm (the default mode httpd is ran under. It is not thread-safe, but doesn’t need to be due to prefork not using threads. It’s located at /usr/lib[64]/httpd/modules/libphp7.so
cli
Contained in the php70w-cli package, this SAPI allows running scripts from the command-line, and also has a built-in web server for development-use. Located at /usr/bin/php
fpm
Contained in the php70w-fpm package, fpm (FastCGI Process Manager) is a scalable FastCGI process, which acts similar to how Httpd prefork mpm works managing it’s forks. Located at /usr/sbin/php-fpm, it is controlled using the /etc/init.d/php-fpm service script
phpdbg
Contained in the php70w-phpdbg package, phpdbg has the ability to debug scripts using breakpoints from the command-line, and also supports remote-debugging using an external Java client for remote communication.
embedded
Contained in the php70w-embedded package, this SAPI allows embedding PHP in other applications. It’s library is located at /usr/lib[64]/libphp7.so
cgi, fastcgi
Contained in the php70w-cli package, these SAPIs are not recommended for use, but are available where needed. They both exist in the binary at /usr/bin/php-cgi.
mod_php TS
(thread safety) Contained in the php70w package, this SAPI integrates into Apache Httpd (2.2.* on RHEL/CentOS 6, 2.4.* on RHEL/CentOS 7). It is the standard SAPI for use with httpd worker mpm. It’s supposed to be thread-safe, but can’t guarantee to be, and certainly not under additional PHP extensions. It’s better to use FastCGI SAPIs than this one. It’s located at /usr/lib[64]/httpd/modules/libphp7-zts.so

Packages
Package
Provides

php70w
mod_php, php70w-zts

php70w-bcmath

php70w-cli
php-cgi, php-pcntl, php-readline

php70w-common
php-api, php-bz2, php-calendar, php-ctype, php-curl, php-date, php-exif, php-fileinfo, php-filter, php-ftp, php-gettext, php-gmp, php-hash, php-iconv, php-json, php-libxml, php-openssl, php-pcre, php-pecl-Fileinfo, php-pecl-phar, php-pecl-zip, php-reflection, php-session, php-shmop, php-simplexml, php-sockets, php-spl, php-tokenizer, php-zend-abi, php-zip, php-zlib

php70w-dba

php70w-devel

php70w-embedded
php-embedded-devel

php70w-enchant

php70w-fpm

php70w-gd

php70w-imap

php70w-interbase
php_database, php-firebird

php70w-intl

php70w-ldap

php70w-mbstring

php70w-mcrypt

php70w-mysql
php-mysqli, php_database

php70w-mysqlnd
php-mysqli, php_database

php70w-odbc
php-pdo_odbc, php_database

php70w-opcache
php70w-pecl-zendopcache

php70w-pdo
php70w-pdo_sqlite, php70w-sqlite3

php70w-pdo_dblib
php70w-mssql

php70w-pear

php70w-pecl-apcu

php70w-pecl-imagick

php70w-pecl-redis

php70w-pecl-xdebug

php70w-pgsql
php-pdo_pgsql, php_database

php70w-phpdbg

php70w-process
php-posix, php-sysvmsg, php-sysvsem, php-sysvshm

php70w-pspell

php70w-recode

php70w-snmp

php70w-soap

php70w-tidy

php70w-xml
php-dom, php-domxml, php-wddx, php-xsl

php70w-xmlrpc

Opcode Caches
The PHP distribution now comes with an opcode cache. This is the Zend Optimizer+ opcode cache, now known as the Zend OPcache extension. This extension is optional, so does not preclude you from using an alternate one.
Due to it being included in the PHP source distribution, it will be well maintained and more suitable for use while other Opcode cache’s are being updated over the coming months.
yum install php70w-opcache

error_reporting E_ALL includes E_STRICT
As mentioned in the PHP 5.4 guide:
You may get a lot more errors coming out of your error logs if by default your error_reporting is set to E_ALL now without explicitly turning off E_STRICT. The default php.ini that comes with the PHP package turns this off by default, but if you are upgrading from an existing installation, your php.ini may not be updated, meaning this will likely be turned on.